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A 


TREATISE 


jAXaAx  / S^ |3^/ 

ANATOMY. 


BY  WIL.IilAB'I  E.  HORIVER,  M.  D. 


ADJ.  PKOP.  AITAT.  UNIT.  PENIfSYLVAlTIA MEMBER  OE  THE  AJIERICAIf  rHII,. 

SOCIETY SERGEOM  AT  THE  PHILADELPHIA  ALMS  HOUSE,  &C. 


n 

IN  TWO  VOLUxMES. 

VOE.  II. 


SECOND  EDITION,  REVISED  AND  CORRECTED 


^ItflaDelphfa: 

CAREY  & EBA. 


1830. 


Oft  ■ V 

J 2- 


KaaCc?!, 


'i  SiiiCrict  uj  J-’Hnnuylvunia,  (ti  wit : 


.*«<*,*  * li'  REMEMBERED,  that  oil  the  seventeenth  day  oi' 
; sEAt.  J October,  in  the  fifty-fii-st  year  of  the  Independence  of  the 
*1  *»***»  United  States  of  America,  A.  D.  1826 — William  E.  Hor- 
ner, of  the  said  district,  hath  deposited  in  this  office  the  title  of  a book, 
the  right  whereof  he  claims  as  author,  in  the  words  following,  to  wit: 


“ A Treatise  on  Special  and  General  Anatomy.  By  William  E.  Hor- 
ner, M.D.,  Adjunct  Professor  of  Anatomy  in  the  University  of  Penn- 
sylvania— Member  of  the  American  Philosophical  Society — Surgeon 
at  the  Philadelphia  Alms  House,  &c.  ‘Multum  adhuc  restat  operis, 
multumque  restabit,  nec  ulli  nato,  post  mille  sxcula  prxcluditur  oc- 
casio  aliquid  adjiciendi. ’ — Seneca,  £/iist.  In  two  volumes.  Yol.  II.” 


In  conformity  to  the  Act  of  the  Congress  of  the  United  States,  en- 
titled, “ An  Act  for  the  Encouragement  of  Learaing,  by  securing  the 
Copies  of  Maps,  Charts,  and  Books,  to  the  Authors  and  Proprietors 
of  such  Copies,  during  the  times  therein  mentioned” — And  also  to  the 
Act,  entitled,  “An  Act  simplementary  to  an  Act,  entitled,  ‘An  Act 
for  the  Encouragement  of  L^earning,  by  securing  the  Copies  of  Maps, 
Charts  and  Books,  to  the  Authors  and  Proprietors  of  such  Copies 
during  the  times  therein  mentioned,’  and  extending  the  benefits  there- 
of to  the  arts  of  designing,  engraving,  and  etching  Historical  and  other 
Prints.” 

D,  CALDWELL, 

Clerk  of  the  Eastern  District  of  Pennsylvania. 


A TREATISE  ON  AKTATOMY. 


BOOK  IV. 


PART  II. 


Organs  of  Assimilation. 


CHAPTER  I. 


OF  THE  ABDOMEN  GENERALLY. 


The  cavity  of  the  abdomen  occupies  the  space  between 
the  inferior  surface  of  the  diaphragm  and  the  outlet  of  the 
pelvis;  a considerable  part  of  it  is,  therefore,  within  the 
periphery  of  the  lower  I’ibs  above,  and  of  the  pelvis  below. 
It  is  completely  separated  from  the  cavity  of  the  thorax  by 
the  diaphragm,  with  the  exception  of  the  foramina  in  the 
latter,  for  transmitting  the  aorta,  the  ascending  cava,  and 
the  oesophagus.  It  is  bounded  below  by  the  iliaci  interni, 
the  psosB,  and  the  levatores  ani  muscles;  on  the  front  and 
sides  by  the  five  pairs  of  muscles  called  abdominal;  and 
behind  by  the  lesser  muscle  of  the  diaphragm,  the  Quadrati 
Lumborum,  the  lumbar  vertebrse,  and  the  sacrum.  The 
figure  of  this  cavity  is,  therefore,  too  irregular  to  admit  of 
a very  rigid  comparison  with  any  of  the  common  objects 
of  life;  but  a little  reflection,  on  the  course  of  its  parietes, 
will  make  it  perfectly  understood.  It  should  be  borne  in 
mind  that  the  very  great  projection  of  the  lumbar  vertebrae, 
forms  for  it  a partial  vertical  septum  behind;  which,,  in  thin 
subjects,  is  almost  in  contact  witli  the  linea  alba  in  front, 
apd  may  be  easily  distinguished  through  the  parietes  of  the 
abdomen,  when  the  intestines  are  empty. 


b 


>» 


OKGAXS  OP  DIGESTIOX. 


The  abdominal  cavity  varies  only,  inconsiderably,  in  its 
vertical  diameter,  owing  to  the  resistance  of  the  diaphragm 
above,  and  of  the  pelvis  below;  neither  does  it  change  be- 
hind, owing  to  the  resistance  of  the  spine,  the  ribs,  and  the 
muscles  there.  But  as  the  introduction  of  food,  the  develop- 
ment of  gazeous  substances  during  digestion,  the  evolution  of 
the  fcBtus,  and  many  other  conditions,  require  some  pro- 
vision for  its  undergoing  an  easy  augmentation  of  volume; 
the  latter  occurs  principally  forwards  and  laterally,  by  the 
yielding  of  the  muscles  and  by  the  extension  of  their  apo- 
neuroses. The  diaphragm  and  the  abdominal  muscles,  for 
the  most  part,  act  alternately;  as  the  former  descends  in 
inspiration,  the  latter  relax  and  give  way  to  the  contents 
of  the  abdomen:  but  in  expiration,  the  abdominal  muscles 
contract,  and  the  diaphragm  is  pushed  upwards  by  the  vis- 
cera. In  attempts  at  the  expulsion  of  faeces,  and  in  par- 
turition, these  muscles  contracting  and  the  diaphragm  being 
fixed  all  at  the  same  moment,  the  cavity  of  the  abdomen 
is  actually  much  diminished. 

The  viscera  contained  in  the  cavity  of  the  abdomen  are 
of  three  kinds.  One  kind  is  engaged  in  digestion  and  as- 
similation; another  in  the  secretion  and  excretion  of  urine; 
and  the  third  in  generation.  As  these  viscera  are  numerous, 
and  it  is  of  great  importance  to  determine  with  precision 
their  position  and  relative  situation,  anatomists  are  agreed 
to  divide  the  cavity  of  the  abdomen  into  several  arbitrary 
regions.  This  is  the  more  advantageous,  as  the  bony  pro- 
minences bounding  the  abdomen  are  not  sufficiently  nume- 
rous and  distinct,  to  afford  those  points  of  departure  and 
of  relation  which  they  furnish  in  other  sections  of  the  body. 
To  obtain  these  regions,  consider  a line  or  plane  as  ex- 
tended across  the  abdomen,  about  two  inches  below  the 
umbilicus,  from  the  superior  part  of  the  crista  of  one  ilium 
as  it  appears  through  the  skin,  to  the  corresponding  point 
of  the  other  side.  Strike  on  each  side  a line  perpendicu- 
lar to  the  preceding  by  commencing  at  the  lower  end  of  the 
anterior  inferior  spinous  process  of  the  ilium,  and  carrying 


OP  THE  ABDOMEN. 


I 


it  up  to  the  diaphragm.  Extend  a fourth  line  across  the 
abdomen  parallel  with  the  first,  and  intersecting  the  two 
last  where  they  come  upon  the  cartilages  of  the  false  ribs. 
It  is  evident  that  these  four  lines  or  planes,  two  horizontal 
and  two  vertical,  will,  with  the  assistance  of  the  parietes 
of  the  abdomen,  furnish  nine  regions:  three  above;  three  in 
the  middle,  and  three  below.  The  central  region  above, 
is  the  Epigastric;  and  on  its  sides  are  the  right  and  the  left 
Hypochondriac.  The  central  region  in  the  middle,  sur- 
rounding the  navel,  is  the  Umbilical;  and  on  its  sides  are 
the  right  and  the  left  Lumbar.  The  central  region  below, 
is  the  Hypogastric;  and  on  its  sides  are  the  right  and  the 
left  Iliac.  There  are  also  some  subordinate  divisions;  for 
example,  the  hollow  in  the  epigastric  region  around  the  en- 
siform  cartilage,  is  called  the  pit  of  the  stomach,  or  Scro- 
biculis  Cordis;  and  for  an  inch  or  two  around  the  sym- 
physis pubis  is  the  region  of  the  pubes,  (Regio  Pubis. ) 

Anatomists  dilfer  among  themselves  about  the  points  of  de- 
parture and  the  position  of  the  lines  separating  the  regions. 
Some  fix  them  at  arbitrary  distances  from  the  umbilicus,  and 
others  assume  the  points  of  the  skeleton.  The  umbilicus  is 
the  most  fallacious  mark,  because  its  elevation  varies  consi- 
derably, according  to  the  state  of  distention  of  the  abdomen, 
it  being  comparatively  higher  when  the  abdomen  is  tumid, 
than  when  it  is  not.  Neither  does  it  answer  to  take  the 
anterior  ends  of  the  last  ribs  as  the  points  for  the  upper  hori- 
zontal line  to  pass  through;  as  they,  sometimes,  are  almost 
as  low  down  as  the  umbilicus  itself.  The  superior  anterior 
spinous  processes  are  also  objectionable  as  the  points  of  de- 
parture for  the  vertical  lines:  as  they  leave  too  much  room 
for  the  central  regions  of  the  abdomen,  and  too  little  for  the 
lateral.  I have,  therefore,  thought  proper  to  substitute  the 
anterior  inferior  spinous  processes. 


General  Situation  of  the  Viscera  of  the  Mdomen. 

When  the  abdomen  is  so  opened  as  to  leave  its  viscera  in 
their  natural  position,  they  will  be  found  as  follows: 


8 


ORGANS  OP  DIGESTION. 


1.  The  Liver,  the  largest  gland  of  the  body,  is  in  the 
right  upper  part  of  the  abdomen,  immediately  below  the 
diaphragm.  It  occupies  nearly  the  whole  of  the  right  hy- 
pochondriac region;  the  upper  half  of  the  epigastric;  and  the 
the  right  superior  part  of  the  left  hypochondriac.  The  an- 
terior extremity  of  the  gall  bladder  projects  beyond  its  an- 
terior margin. 

2.  The  Spleen  is  situated  in  the  posterior  part  of  the  left 
hypochondriac  region. 

3.  The  Stomach,  in  a moderate  condition  of  distention,  oc- 
cupies the  lower  half  of  the  epigastric  region,  and  the  right 
inferior  portion  of  the  left  hypochondriac. 

4.  The  smaller  Intestine,  when  moderately  distended 
by  flatus,  occupies  the  umbilical  region,  the  hypogastric, 
portions  of  the  iliac  on  each  side,  and  also  the  upper  part 
of  the  cavity  of  the  pelvis,  when  the  viscera  of  the  latter 
are  empty. 

5.  The  Large  Intestine  traverses  the  cavity  of  the  abdo- 
men in  such  manner  as  to  perform  almost  the  entire  circuit 
of  it.  It  begins  in  the  right  iliac  region  by  receiving  the 
lower  extremity  of  the  small  intestine,  it  then  ascends 
through  the  right  lumbar  and  the  right  hypochondriac, 
passes  into  the  lower  part  of  the  epigastric  or  into  the  up- 
per of  the  umbilical,  according  to  the  state  of  distention  of 
the  stomach;  thence  it  gets  into  the  left  hypochondriac,  be- 
ing fixed  higher  up  there  than  in  the  corresponding  region 
of  the  other  side;  afterwards  it  goes  down  into  the  left  lumbar 
and  into  the  left  iliac;  thence  it  passes  into  the  pelvis,  and, 
descending  in  front  of  the  sacrum,  terminates  in  the  orifice 
called  anus. 

fi.  The  Caul  or  Omentum  is  a membrane,  of  various  densi- 
ties, in  difierent  individuals,  and  lies  in  front  of  the  intes- 
tine,s.  Sometimes  it  is  found  spread  over  the  latter  like  an 


OF  THE  ABDOMEN. 


9 


apron,  but  on  other  occasions  is  drawn  up  into  the  umbili- 
cal region,  forming  a ridge  across  it. 

7.  The  Pancreas  lies  transversely  in  the  lower  back  part 
of  the  epigastric  region.  It  extends  from  the  left  hypo- 
chondriac region  to  the  right  side  of  the  spine,  and  is  placed 
behind  the  stomach,  so  as  to  be  covered  by  it. 

8.  The  Kidneys  and  the  Capsulse  Renales,  two  in  number 
each,  are  placed  in  the  posterior  part  of  the  lumbar  region 
on  the  side  of  the  spine. 

9.  The  Urinary  Bladder  and  the  Rectum,  in  the  male, 
occupy  the  cavity  of  the  pelvis,  and  in  the  female  between 
them  are  placed  the  uterus,  the  ovaries,  and  the  vagina. 

As,  in  the  dissection  of  the  abdominal  viscera,  the  sub- 
ject is  commonly  placed  on  its  back,  so  the  preceding 
description  is  made  out  with  a strict  reference  to  that  po- 
sition. Some  modification  in  the  shape  of  the  abdomen, 
as  well  as  in  the  situation  of  its  contents  occurs  in  standing 
upright.  The  front  of  the  abdomen  becomes  more  protu- 
berant, the  lumbar  vertebras  make  a greater  projection  for- 
wards. The  pelvis  is  so  adjusted,  in  order  to  bring  the 
acetabula  directly  in  the  line  of  support  to  the  spine,  that 
the  convexity  of  the  sacrum  presents  almost  upwards, 
and  the  superior  straight  looks  forwards  and  upwards  to- 
wards the  navel,  so  that  much  of  the  weight  of  the  viscera 
is  thrown  upon  the  pubes.  In  this  attitude  most  of  the  vis- 
cera descend,  but  more  obviously  the  liver  from  its  weight, 
size,  and  solidity.  Poi’tal  has  verified  this  descent  by  com- 
paring the  thrusts  of  poignards  into  the  liver  in  the  ei’ect, 
with  those  inflicted  in  the  horizontal  position.  He  also 
asserts  that  the  same  may  be  ascertained  in  the  living  body 
by  applying  the  fingers  under  the  false  ribs,  and  then  di- 
recting the  person  to  change  from  the  recumbent  into  the 
vertical  position.  The  spleen  aflfords  the  same  results  when 
it  is  slightly  enlarged,  and  the  descent  of  the  liver  and  spleen 
will  of  course  ensure  that  of  the  stomach  and  intestines.  Ac- 


10 


ORGANS  OF  DIGESTION. 


cording  to  Winslow,  the  pain  and  faintness  which  are  felt 
after  long  abstinence,  come  from  the  vacuity  of  the  sto- 
mach alid  intestines,  which  thereby  withdraw  their  support 
from  the  liver,  and  permit  it  to  drag  upon  the  diaphragm. 

The  presence  of  flatus  in  the  stomach  and  intestinal  canal, 
seems  to  be  entirely  natural  to  them;  for  it  is  comparatively 
rare  to  find  them  destitute  of  it,  even  when  they  contain 
no  food  or  fteces.  The  large  intestine  is,  however,  more 
frequently  found  contracted  or  empty  than  the  small.  Owing 
to  the  flexible  character  of  a considerable  portion  of  the  ab- 
dominal parietes,  the  latter  by  their  own  contraction  as  well 
as  by  atmospheric  pressure,  are  kept  in  close  contact  with 
the  viscera,  and  the  viscera  again,  by  the  same  influence, 
are  kept  in  close  contact  with  one  another;  so  that  notwith- 
standing the  irregularity  of  their  forms  and  the  fluctuating 
size  of  the  hollow  ones,  there  is  no  unoccupied  space  in  the 
cavity  of  the  belly. 

Several  instances  are  reported  by  anatomists,  in  which  a 
total  transposition  of  the  abdominal  viscera  has  occurred,  so 
that  those  which  belonged  to  tbe  right  side  were  placed  in 
the  left.*  They  are,  however,  exceedingly  rare;  in  proba- 
bly more  than  fifteen  hundred  observations,  I have  never 
met  with  one  of  the  kind. 


CHAPTER  II. 

OF  THE  PERITONEUM  AND  SEROUS  MEMBRANES 
GENERALLY. 

SECT.  I. — OF  THE  PERITONEUM. 

The  sides  of  the  abdomen  are  lined,  and  its  viscera  are 
covered  by  a membrane  called  Peritoneum.  As  the  reflec- 
tions of  this  membrane,  by  being  thrown  over  the  periphery 
of  almost  every  viscus  of  the  abdomen,  consequently  assume 


Portal,  Haller,  Sandifort,  &c. 


OF  THE  PERITONEUM. 


11 


the  same  shape;  and  as  it  lines,  without  exception,  the  in- 
terior surface  of  every  part  of  the  abdomen,  its  form  is  ex- 
tremely complicated,  and  can  only  be  judged  of  accurately 
after  the  study  of  the  viscera  is  completed.  For  the  pre- 
sent it  will  only  be  necessary  to  give  the  outline  of  it,  leav- 
ing the  details  to  each  appropriate  occasion. 

In  man,  it  is  a complete  sac,  having  no  hole  in  it;  but 
in  woman,  its  cavity  communicates  externally  through  the 
fallopian  tubes.  It  has  a double  use;  In  consequence  of 
covering  the  viscera,  it  is  so  reflected  from  them  to  the  sides 
of  the  abdomen,  that  its  processes  keep  the  viscera  in  their 
proper  places,  and  therefore  answer  as  ligaments:  again,  its 
internal  surface  being  smooth,  indeed  highly  polished,  and 
continually  lubricated  by  a thin,  albuminous  fluid,  corres- 
ponding with  the  synovial  membrane  of  the  joints,  the  mo- 
tions which  the  viscera  have  upon  each  other  in  exercise, 
and  in  the  peristaltic  movements  of  the  bowels,  are  much 
facilitated. 

The  manner  in  which  a double  night-cap  is  applied  to 
the  head,  will  afford  the  easiest  conception  of  the  reflections 
of  the  peritoneum.  If  there  were  only  one  viscus  in  the 
belly,  and  that  of  a somewhat  regular  outline,  as  the  spleen, 
the  comparison  would  be  rigid,  and  perfectly  appreciable. 
One  part  of  the  cap  is  close  to  the  head,  and  compares  with 
the  peritoneal  coat  of  the  spleen;  the  other  is  loose,  and  is 
equivalent  to  the  peritoneum,  where  it  is  in  contact  with  the 
parietes  of  the  belly.  It  is  also  evident  from  this,  that 
none  of  the  viscera  can  be  said  to  be  within  the  cavity  of 
the  peritoneum;  that  they  are  all  on  its  outside;  and  that 
a viscus,  in  getting  a coat  from  the  peritoneum,  merely 
makes  a protrusion  into  its  cavity.  Starting  with  this  sim- 
ple proposition,  it  is  easy  to  conceive  of  a second,  a third 
body,  and  so  on,  deriving  an  external  coat  from  a protru- 
sion into  the  same  sac.  Admitting  these  bodies  to  be  spheres, 
the  proposition  is  immediately  intelligible;  and,  as  a last 
step  from  it,  the  idea  is  not  rendered  much  more  complex 
by  substituting  any  bodies,  even  the  most  irregular  in  form, 
for  these  spheres.  Such,  then,  is  the  fact  in  regard  to  the 


12 


OKGANS  OP  DIGESTION. 


stomach,  intestines,  &c. ; they  all,  with  exceptions  to  be 
stated,  derive  an  external  coat  from  the  peritoneum. 

The  Peritoneum  is  for  the  most  part  smoothly  spread 
upon  tlie  interior  surface  of  the  abdominal  muscles.  It  ad- 
heres to  them  with  considei’able  firmness  by  means  of  in- 
tervening cellular  substance:  this  adhesion,  where.it  closes 
the  posterior  opening  of  the  umbilicus,  is  unusually  strong. 
Below,  the  uniformity  of  the  membrane  as  it  descends  from 
the  navel  to  the  pelvis  is  interrupted  by  its  being  reflected 
over  the  urachus,  and  over  the  remains  of  the  umbilical  ar- 
tery on  either  side.  Where  the  urachus  is,  it  forms  an  ob- 
long prominent  ridge  reaching  to  the  upper  extremity  of 
the  bladder;  and,  as  regards  each  umbilical  artery,  the  du- 
plicature  is  of  variable  breadths  in  different  individuals;  but 
always  forms  a well  marked  falciform  process,  reaching 
from  near  the  umbilicus  to  the  lower  side  of  the  bladder, 
and  dividing  the  inguinal  region  into  two  parts  or  fossae, 
one  next  to  the  pubes,  and  the  other  nearer  to  the  ilium. 
In  the  undistended  state  of  the  bladder  the  peritoneum 
reaches  to  the  pubes,  is  reflected  from  the  latter  to  the  up- 
per, and  then  goes  over  the  posterior  surface  of  the  blad- 
der. In  the  male  it  goes  from  the  posterior  lower  end  of 
the  bladder  to  the  rectum,  but  in  the  female  it  does  not 
descend  so  low  there,  and  passes  from  the  bladder  to  the 
vagina  and  uterus,  and  afterwards  to  the  rectum. 

In  the  concavity  of  the  ilium,  and  in  the  lumbar  regions, 
the  peritoneum  is  attached  by  long  loose  cellular  substance, 
which  permits  it  to  be  stripped  off  easily,  simply  by  tear- 
ing. In  tliese  several  regions  it  encounters  the  colon,  over 
which  it  is  reflected,  and  thereby  forms  the  Mesocolon; 
thence  it  passes  in  front  of  the  kidneys,  but  separated  from 
them  by  a thick  layer  of  cellular  and  adipose  matter,  and 
immediately  afterwards  it  is  thrown  into  a long  duplicature, 
extending  obliquely  across  the  lumbar  vertebrae  from  above 
downwards,  and  to  the  right  side.  This  duplicature  in- 
cludes the  small  intestines,  and  is  the  Mesentery. 

In  the  highest  regions  of  the  abdomen,  the  peritoneum  is 
in  the  greater  part  of  its  extent  uniformly  reflected  over 


ANATOMY  OP  SEROUS  MEMBRANES. 


13 


the  concave  surface  of  the  diaphragm,  and  adheres  so  close- 
ly to  it,  as  to  require  a cautious  and  protracted  dissection  for 
its  entire  removal.  As  the  remains  of  the  umbilical  vein 
of  the  foetus  are  still  found,  but  in  a ligamentous  condition, 
going  from  the  navel  to  the  under  surface  of  the  liver,  their 
existence  gives  rise  to  a broad  falciform  duplicature  of  pe- 
ritoneum, which  passes  from  the  upper  half  of  the  linea  alba 
and  from  the  middle  line  of  the  diaphragm  to  the  liver. 
Another  line  of  attachment,  or  of  reflection,  of  this  mem- 
brane to  the  liver,  is  found  all  along  the  posterior  margin 
of  the  latter.  In  the  same  region  it  is  also  reflected  from 
the  diaphragm  to  the  spleen  and  to  the  stomach.  Such  is 
the  general  account  of  the  course  of  the  peritoneum.  Each 
of  the  duplications  has  a distinct  name,  and  some  peculiari- 
ty of  organization  or  of  relation,  which  will  require  a spe- 
cific description  and  a frequent  allusion  to  it. 

It  is  proved,  from  what  has  been  said,  that  the  perito- 
neum is  a single  and  a complete  sac,  and  that  with  the  ex- 
ception stated  of  the  fallopian  tubes,  there  is  no  hole  in  it 
either  for  the  passing  of  blood  vessels,  nerves,  or  viscera. 
And  that  it  is  so  folded  over  the  abdominal  viscera,  that  with 
patience  and  sufficient  address,  one  might  remove  it  from 
their  surface  and  extract  them,  without  even  laying  open  its 
cavity:  an  experiment  said  to  have  been  successfully  ac- 
complished by  Nicholas  Massa*  and  some  other  anatomists. 

SECT.  II. GENERAL  ANATOMY  OF  THE  SEROUS  MEMBRANES. 

As  the  peritoneum  presents  one  of  the  best  examples  of  a 
numerous  class  of  membranes,  called  Serous,  it  will  be 
useful  at  this  point  to  inquire  into  their  general  condition 
and  properties.  They  are,  for  the  most  part  thin,  and 
strongly  resemble  compressed  cellular  membrane,  having 
been,  indeed,  by  some  anatomists  considered  as  such.  They 
invariably  assume  the  form  of  perfect  sacs,  and  as  they  are 

* Annot.  Liber.  Introduct.  an.  1539.  Uortal. 

VoL.  II. — 3 


M 


ORGANS  OP  DIGESTION. 


found  in  all  parts  of  the  body,  they  are  kept  distinct  from 
each  other.  The  arachnoid  membrane  of  the  brain,  the  pe- 
ricardium, the  pleura,  the  synovial  membi’anes  of  the  joints, 
the  bursa;  mucosae  of  tendons,  the  peritoneum,  and  the 
tunica  vaginalis  testis,  belong  to  this  class.  They  are  not 
all  of  the  same  thickness,  as  some  are  much  more  dense 
than  others;  they  adhere  to  neighbouring  parts  by  a lamina 
of  cellular  substance,  which  is  also  of  variable  thickness  and 
ductility;  indeed,  on  some  occasions,  it  is  not  entirely  dis- 
tinct, from  its  extreme  shortness  and  tenuity. 

As  the  serous  membranes  are  only  displayed  over  the 
surface  of  the  organs  which  they  cover,  after  the  manner  of 
a double  night  cap  drawn  over  the  head;  their  cavity  always 
remains,  notwithstanding  it  is  variously  modified  by  the 
shape  of  the  organs  protruded  into  it;  and  has  its  parietes 
in  contact,  owing  to  external  compression.  They  are  en- 
tirely distinct  from  the  intimate  or  peculiar  structure  of  the 
organs  covered,  and  are  displayed  over  those  of  the  most 
dissimilar  functions,  as,  for  example,  the  intestines  and  the 
liver.  A sac  of  this  description,  then,  is  of  infinite  impor- 
tance in  establishing  between  organs  which  border  upon  one 
another,  a strong  demarcation:  and  consequently  in  warding 
off'  any  injurious  influence  which  their  dissimilar  natures, 
would  otherwise  cause  them  to  have  upon  each  other.  Im- 
portant organs  are,  therefore,  invariably  thus  insulated,  so 
that  whether  in  a healthy  or  in  a diseased  state,  their 
actions  are  carried  on  within  themselves;  and  not  only  so, 
but  it  is  even  possible,  and  indeed  is  found  in  morbid  dis- 
sections, every  day;  that  an  organ  may  be  diseased  while  its 
serous  covering  is  unaffected;  or  the  reverse.  Thus  we 
have  large  suppurations  in  the  liver,  while  its  peritoneal 
coat  is  healthy;  large  accumulations  of  water  in  the  tunica 
vaginalis  testis,  while  the  testicle  itself  is  sound;  in  the  tho- 
rax, with  sound  lungs  and  heart;  in  the  abdomen,  with  vis- 
cera generally  sound;  in  the  joints,  without  an  affection  of 
the  bones.  Nothing  is  more  common  than  to  see  partial 
adhesions,  the  result  of  inflammation,  causing  the  opposite 
sides  of  these  sacs  to  adhere,  without  any  evident  constitu- 


ANATOMY  OF  SEROUS  MEBIBRANES. 


15 


tional  or  visceral  derangement;  and  some  of  our  plans  of 
cure,  as  in  the  hydrocele,  are  founded  upon  this  well  es- 
tablished fact. 

The  serous  membranes  are  throughout  thin,  transparent, 
and  white:  in  some  points  their  tenuity  is  so  extreme  that 
they  seem  to  consist  simply  in  a smooth,  polished  surface, 
spread  over  parts;  this  is  strikingly  the  case  on  the  interior 
face  of  the  dura  mater,  on  the  ventricles  of  the  brain,  and 
on  the  cartilages  of  the  joints.  The  evidence  of  their  ex- 
tension there,  is  consequently  derived  principally  from  in- 
duction; and  from  morbid  alteration,  in  which  they  become 
thickened.  Their  internal  surface,  in  a natural  state,  is  al- 
ways smooth,  highly  polished,  shining;  and  being  also  lu- 
bricated by  its  peculiar  unctuous  secretion,  the  opposite  pa- 
rietes,  when  they  come  into  contact,  glide  freely  upon  each 
other;  a circumstance  indispensable  to  the  free  action  of  the 
joints,  and  to  the  peristaltic  motion  of  the  bowels.  Bordeu 
has  asserted,  that  these  remarkable  characters  of  the  serous 
membranes,  depend  upon  the  compression  and  the  friction 
to  which  they  are  continually  exposed:  but  to  this  opinion 
the  argument  of  Bichat  is  unanswerable,  that  in  their  ear- 
liest observable  period  in  the  foetus,  they  have  the  same  po- 
lish. 

The  fluid  secreted  from  the  serous  membranes  resembles, 
strongly,  the  serosity  of  the  blood.  It  is  poured  out  conti- 
nually by  the  exhalent  orifices,  and  in  a short  time  after- 
wards is  taken  up  by  the  absorbents,  so  that  in  a natural  state 
there  is  seldom  more  than  sufficient  to  lubricate  the  surfaces 
of  the  membrane.  When  the  abdomen  of  an  animal  recent- 
ly killed  is  exposed  to  the  air,  this  fluid  rises  in  the  form  of 
a vapour.  The  several  experiments,  as  the  application  of 
heat,  mineral  acids,  and  so  on,  which  prove  the  abundance 
of  albumen  in  the  serum  of  the  blood,  produce  the  same  re- 
sults when  applied  to  the  secretion  from  the  serous  mem- 
branes. 

The  system  of  serous  membranes  has  been  considered  by 
Bichat  and  others  as  only  a modification  of  cellular  mem- 
brane, for  the  following  reasons.  The  inflation  of  air  into 


16 


ORGANS  OF  DIGESTION. 


the  cellular  tissue  subjacent  to  them,  reduces  them  to  the 
form  of  cellular  substance.  Protracted  maceration  produces 
the  same  effects  with  more  certainty  and  precision.  When 
cellular  membrane  is  inflated,  the  parietes  of  the  distended 
cells  resemble  strongly  the  finest  parts  of  the  serous  system, 
as  the  arachnoid  membrane.  There  is  an  identity  of  func- 
tions and  of  affections,  for  they  are  both  continually  engaged 
in  the  great  work  of  exhalation  and  absorption,  and  suffer 
in  the  same  way  from  dropsical  effusion,  with  the  only  dif- 
ference that  the  latter  is  more  amassed  in  the  one  than  in 
the  other.  My  own  experience  goes  to  prove,  that  dropsy 
very  seldom  manifests  itself,  to  any  extent,  in  the  cellular 
tissue  without  also  going  to  the  serous  cavities,  and  the  re- 
verse. The  serous  membranes  are  also  of  a uniform  tex- 
ture, like  cellular  substance,  and  present  no  appearance  of 
fibres. 

The  serous  membranes  are  furnished  with  a great  abun- 
dance of  exhalent  pores,  and  of  absorbents,  which  carry  on 
their  functions  with  great  activity.  They  receive  only  the 
colourless  part  of  the  blood,  whence  the  uniform  transpa- 
rency of  these  membranes.  In  order  to  establish  the  exist- 
ence of  exhalent  pores,  by  strangulating  a piece  of  intestine 
with  a ligature  for  thirty-six  or  forty-eight  hours,  they  be- 
come evident,  by  dilating  themselves  so  as  to  receive  red 
blood.  A fine  coloured  injection  produces  the  same  result; 
and  also  moistens,  by  the  escape  of  its  watery  particles,  the 
surface  of  the  intestine,  by  a very  fine  halitus  or  dew.  The 
intestine  of  a living  animal,  if  wiped  perfectly  dry,  will, 
after  the  same  way,  soon  present  another  coat  of  serosity 
on  its  surface.  The  existence  of  absorbents  to  a great  ex- 
tent in  them,  may  also  be  equally  well  proved,  as  they  very 
readily  receive  a mercurial  injection,  which  diffuses  itself 
over  their  whole  surface,  and  causes  them  to  have  the  ap- 
pearance of  being  formed  entirely  of  such  vessels.  The 
readiness  with  which  fluid  effused  into  their  cavities  is  taken 
up,  is  another  proof  of  the  same.  Bichat  once  saw  them 
distended  with  air  in  a man  who  had  become  emphysema- 
tous from  poisoning.  Mascagni  has  frequently  found  them 


ANATOMY  OP  SEROUS  MEMBRANES. 


17 


distended  with  the  fluid  of  dropsical  collections,  which  he 
recognised  by  its  colour.  It  happened  to  the  same  anato- 
mist to  find  in  two  bodies,  where  there  had  been  an  eflusion 
of  blood  into  the  thorax,  the  absorbents  of  the  lungs  gorged 
with  blood.  This  faculty  of  absoi'ption  ma3>-  sometimes  be 
proved  to  continue  for  some  hours  after  death,  by  keeping 
an  animal  in  a warm  bath.  Mascagni  asserts,  that  he  has 
witnessed  its  continuance  for  fifteen,  thirty,  and  even  for 
forty-eight  hours;  it  is  not  improbable,  however,  that  there 
was  some  illusion  in  these  instances. 

It  is  more  than  probable  that  the  serous  membranes  are 
entirely  deprived  of  red  blood  vessels;  the  latter  unques- 
tionably exist,  in  great  numbers,  on  the  exterior  surface, 
where  they  creep  through  the  cellular  substance,  but  they 
may  be  removed  with  a scalpel  without  affecting  the  conti- 
nuity of  these  membranes.  Again,  where  these  mem- 
branes are  free  and  unconnected  on  both  surfaces,  as  in 
some  parts  of  the  tunica  arachnoidea,  there  is  no  appearance 
of  red  blood  vessels.  In  hernial  protrusions,  where  there 
is  a considerable  prolapse  of  peritoneum,  the  blood  vessels 
which  are  found  abundantly  about  the  neck  of  the  sac,  do 
not  follow  the  course  of  the  protrusion.  Unquestionably 
some  communication  exists  between  the  arterial  system  and 
the  serous  membranes,  as  proved  by  exhalation  and  morbid 
phenomena,  but  the  mode  is  not  well  ascertained. 

In  common  hernia  and  in  dropsy,  the  serous  membranes 
become  more  thick:  from  my  dissections  I am  inclined  to 
think,  that  this  change  is  not  so  great  as  is  generally  allowed; 
for  most  frequently,  by  a careful  removal  of  the  exterior 
cellular  substance,  they  have  been  I’estored  to  their  primi- 
tive condition.  In  other  cases,  as  in  large  umbilical  hernias, 
they  are  so  much  attenuated  as  to  be  found  with  difficulty. 

The  power  of  extension  which  these  membranes  possess, 
is  strikingly  marked  in  dropsical  effusions,  in  the  develop- 
ment of  tumours,  and  in  pregnancy;  but  much  of  this  ap- 
parent quality  is  derived  from  their  mode  of  attachment  to 
adjacent  parts,  whereby  they  are  drawn  from  one  surface 
to  cover  another.  This  happens  daily  where  the  perito- 


18 


ORGANS  OF  DIGESTION. 


neum  is  drawn  from  the  lower  part  of  the  abdomen  to  co- 
ver the  bladder  in  the  distentions  of  the  latter;  in  pregnancy, 
where  it  is  drawn  upon  the  growing  uterus  from  all  the 
neighbouring  parts;  and  in  the  distentions  of  the  stomach 
by  food  or  flatus,  where  it  is  drawn  up  from  the  omenta. 
The  serous  membranes  have  also  a power  of  contraction 
equal  to  that  of  their  extension;  but  it  should  not  be  con- 
founded with  that  condition  where  they  are  simply  restored 
by  the  connecting  cellular  substance,  to  the  surfaces  where 
they  originally  belonged. 

The  sensibility  of  the  serous  membranes,  from  the  want 
of  nerves  in  them,  is  extremely  obscure  in  a natural  state, 
and  only  affords  an  imperfect  sensation  of  touch.  This  is 
proved  by  the  impunity  with  which  they  may  be  irritated 
on  living  animals.  But,  when  the  condition  of  inflammation 
is  once  established,  they  feel  the  most  acute  and  distressing 
pain.  Though  they  resist  most  frequently,  and  for  a long 
time,  disease  in  adjacent  parts,  yet  it  not  unfrequently  is  ex- 
tended to  them  at  lost.  In  such  cases  it  is  generally  a local 
instead  of  a universal  affection,  which  is  communicated  to 
them:  Thus,  in  the  cancer  and  scirrhus  of  the  uterus;  in 
disease  of  the  spleen,  and  so  on;  the  portion  of  peritoneum 
nearest  the  affected  organ,  manifests  the  marks  of  the  disease 
by  preternatural  adhesions  and  by  disorganization,  without 
the  whole  membrane  being  involved. 

As  the  serous  system  consists  in  many  species  of  sacs, 
so  each  of  them  has  some  peculiarity  of  organization,  of 
attachment,  and  of  vital  properties,  which  are  stated  else- 
where in  the  account  of  the  species  themselves. 

SECT.  III. — OF  THE  OMENTA. 

There  are  four  processes  of  the  peritoneum,  each  of 
which  is  designated  under  the  term  Omentum,  Epiploon, 
or  Caul. 

1.  The  Omentum  Minus  or  the  Hepatico-Gastricum,  ex- 
tends, as  its  name  imports,  between  the  liver  and  the  sto- 


THE  OMENTA. 


19 


niach.  It  begins  at  the  transverse  fissure  of  the  liver,  and 
proceeds  from  it,  from  the  right  side  of  the  lobulus  spigelii, 
the  front  of  which  it  conceals,  and  from  the  inferior  poste- 
rior face  of  the  tendinous  centre  of  the  diaphragm;  it  is  at- 
tached to  the  lesser  curvature  of  the  stomach  in  all  the  space 
between  the  cardiac  and  the  pyloric  orifices.  Its  right  mar- 
gin reaches  beyond  the  pylorus  to  the  duodenum,  and  in- 
cludes the  vessels  going  to  the  liver,  and  the  biliary  ducts; 
in  consequence  of  which,  this  margin  is  called  the  Capsule 
of  Glisson. 

The  two  laminae  which  compose  it  are  thin  and  transpa- 
rent, and  have  but  little  fat  in  them;  in  approaching  the  sto- 
mach they  become  very  distinct  from  each  other,  and  re- 
ceive between  them  the  superior  coronary  vessels  of  the 
stomach.  One  lamina  then  goes  before  the  stomach  and  the 
other  behind,  in  the  form  of  a peritoneal  covering.  These 
laminae  having  covered,  in  that  way,  the  anterior  and  the 
posterior  surface  of  the  stomach,  unite  again  on  the  greater 
curvature  of  the  latter,  to  form  the  beginning  of  the  omen- 
tum majus. 

2.  The  Omentum  Majus  or  Gastro-Colicum,  as  indica- 
ted by  its  name,  is  connected  at  one  end  all  along  the  greater 
curvature  of  the  stomach,  and  by  the  other  along  the  trans- 
verse part  of  the  colon.  As  it  commences  by  two  laminae, 
so  it  is  continued  throughout  in  the  same  way.  It  is  com- 
monly found  more  or  less  spread  on  the  front  surface  of  the 
small  intestines,  but  occasionally  it  is  tucked  up  in  the  epi- 
gastric region.  When  fairly  spread  out  either  naturally  or 
artificially,  its  course  will  be  found  as  follows:  It  first  of  all 
descends  from  the  stomach  to  the  pelvis;  it  then  turns  up- 
wards so  as  to  reverse  its  course,  and  continues  to  ascend 
till  it  reaches  the  colon.  Its  two  laminae  then  separate  and 
receive  the  colon  between  them,  so  that,  in  this  respect,  the 
arrangement  is  entirely  conformable  to  what  happens  to  the 
stomach.  The  subsequent  continuation  of  these  laminae  is 
the  mesocolon,  which  will  be  more  particularly  described. 

As  the  omentum  majus  consists  of  two  laminae  in  its 
whole  extent,  it  is  clear  that  it  resembles  a flattened  bag 


20 


OllGANS  OK  DIGESTION. 


lined  by  another  bag,  so  that  in  its  whole  thickness,  when 
held  between  the  fingers,  there  are  four  laminse.  It  is  an 
irregular  quadrilateral  membrane,  which  in  corpulent  sub- 
jects, is  interspersed  with  a great  deal  of  fat;  but,  in  such 
as  are  emaciated,  it  is  wholly  destitute  of  the  latter;  and  in- 
stead of  being  entire  in  its  parietes,  is  a delicate  reticulated 
membrane,  so  that  the  rule  about  the  integrity  of  the  peri- 
toneum is  not  fully  accurate  as  applied  to  this  section  of  it. 
On  the  right  side  it  is  continuous  with-  the  omentum  coli- 
cum,  and  on  the  left  with  the  omentum  gastro-splenicum. 

3.  The  Omentum  Colicum  may  be  considered  as  a con- 
tinuation of  the  omentum  majus  along  the  ascending  and  a 
part  of  the  transverse  colon.  In  some  rare  cases,  (for  in 
my  own  observations  I have  not  met  with  the  arrangement,) 
its  origin  is  continued  downwards  to  the  coecum,  and  at  its 
left  margin  is  extended  along  the  transverse  colon  to  the 
.spleen.  Much  more  commonly  it  is,  as  stated,  simply 
an  appendage  of  the  great  omentum,  or  its  right  flank,  ad- 
vancing for  a short  distance  along  the  ascending  colon. 

It  consists  of  but  two  laminae  in  all,  commonly  contain- 
ing fat,  but  in  this  respect  subject  to  the  same  rule  as  the 
omentum  majus. 

4.  The  Omentum  Gastro-Splenicum  is  the  left  flank  or 
margin  of  the  omentum  majus,  extended  from  the  great  end 
of  the  stomach  to  the  spleen.  It  of  course  consists  of  but 
two  laminae,  which  contain  between  them  the  splenic  vessels 
and  the  vasa  brevia. ' 

By  looking  for  the  posterior  end  of  the  gall  bladder,  and 
then  passing  a finger  under  the  right  margin  of  the  hepati- 
cogastric  omentum,  or,  in  other  words,  under  the  capsule 
of  Glisson,  where  it  passes  from  the  liver  to  the  duodenum; 
the  finger  will  be  found  to  have  insinuated  itself  behind  the 
stomach,  and,  by  being  directed  downwards,  will  be  thrust 
into  the  sac  or  cavity  of  the  great  omentum.  In  children, 
where  the  latter  is  less  reticulated  than  in  adults,  and  con- 
sequently more  entire,  a large  blow-pipe  introduced  at  the 


OP  THE  OMENTA. 


21 


same  point  will  enable  one  to  inflate  this  cavity,  and  to  se- 
parate its  anterior  from  its  posterior  wall.  This  aperture, 
called  the  foramen  of  Winslow,  is  precisely  the  means  by 
which  the  internal  or  lining  lamina  of  the  omentum  majus 
is  introduced,  so  as  to  make  this  process  of  peritoneum 
double  throughout  its  whole  parietes.  Though  this  fact  of 
duplicity  is  generally  conceded,  no  author  heretofore,  to 
my  knowledge,  has  pointed  out  satisfactorily  the  means; 
and  for  the  suggestion  of  it,  I am  indebted  to  a learned  and 
zealous  member  of  the  profession.  Dr.  Hugh  Hodge  of  this 
city.  Struck,  at  an  early  period  of  his  studies,  with  the 
difficulty  of  tracing  a double  sac  to  the  omentum  majus,  out 
of  a single  membrane  of  the  peritoneum,  this  suggestion 
was  happily  made  by  him,  to  remove  the  difficulties  of  other 
explanations.  An  attempt  at  a diagram  formed  upon  any 
other  principle  I have  invariably  seen  to  fail.  If  the  reader 
has  conceived  the  idea,  the  inference  will  he  plain,  that  the 
lining  lamina  of  the  omentum  majus  is  continued  as  a com- 
mon peritoneal  covering  over  the  posterior  face  of  the  sto- 
mach, and  then  forms  the  posterior  lamina  of  the  hepatico- 
gastric  omentum.  It  will  also  be  plain  that  the  same  lamina, 
having  reached  the  colon  in  its  return,  continues  afterwards 
as  the  upper  lamina  of  the  transverse  mesocolon. 

From  what  has  been  said  concerning  the  general  qualities 
of  the  peritoneum,  it  is  to  he  understood  that  though  it  en- 
joys much  power  of  gradual  extension:  nevertheless  this 
quality  is  not  sufficient  to  enable  it  to  endure,  without  a 
special  provision;  the  sudden  and  extensive  dilatations  to 
which  the  stomach  and  bowels  are  exposed,  from  the  intro- 
duction of  food  and  from  the  evolution  of  gases  during  di- 
gestion, Of  all  the  coats  of  these  organs,  it  is  the  least  ex- 
tensible and  contractile;  its  rupture,  therefore,  is  guarded 
against  by  one  invariable  rule.  For  example:  as  the  mus- 
cular and  other  coats  of  the  stomach  dilate,  the  peritoneum 
is  drawn  from  the  omentum  minus  and  majus  to  cover  the 
stomach;  therefore,  as  the  stomach  enlarges,  the  omenta  di- 
minish; and  as  the  stomach  decreases,  the  omenta,  by  the 
restoration  of  peritoneum,  resume  their  primitive  size.  In 
Voi.  II.— 4 


JO 


ORGANS  OF  DIGESTION. 


tliis  way  the  uterus,  notwithstanding  its  great  augmentatiorr 
in  tlie  progress  of  pregnancy,  still  keeps  itself  covered  by 
peritoneum,  from  the  ability  of  tbe  latter,  as  mentioned,  to 
slide  from  one  part  and  to  apply  itself  to  another.  The 
true  intention,  then,  of  the  apparently  useless  length  of 
many  processes  of  the  peritoneum,  is  explained,  by  their 
being  a provision  for  the  augmentation  of  the  hollow  vis- 
cera of  the  abdomen,  in  tbe  discharge  of  their  natural  func- 
tions. Adopting  this  explanation  as  the  basis  of  our  obser- 
vations, we  shall  find  that  according  to  the  probable  or  event 
possible  augmentation  of  a viscus,  so  are  its  peritoneal  at- 
tachments. The  stomach,  which  next  to  the  uterus  enlarges 
more  than  any  other  viscus,  gets  its  subsidiary  supply  of 
peritoneum  from  the  length  of  the  omentum  minus  and  ma- 
jus;  the  colon,  which  is  next  in  order,  is  supplied  from  the 
length  of  its  mesocolon;  the  small  intestines,  which  are 
next,  from  the  length  of  the  mesentery.  The  latter,  how- 
ever, would  be  too  long  for  that  simple  purpose;  but  the  ob- 
jection is  removed,  by  recollecting  that  the  mesentery  has 
also  to  accommodate  numerous  chains  of  lacteal  glands, 
through  which  the  chyle  must  pass  in  its  elaboration,  before 
it  is  fit  to  enter  into  the  general  circulation.  The  liver, 
being  of  a size  almost  stationary,  has  its  peritoneal  attach- 
ments proportionally  short;  and  its  peritoneal  covering, 
from  the  shortness  of  the  connecting  cellular  substance,  is 
disqualified  from  sliding.  The  spleen  is  in  the  same  pre- 
dicament with  the  liver,  except  that  its  size  is  not  station- 
ary; but,  in  this  case,  the  peritoneum  presents  a phenome- 
non entirely  remarkable:  it  wrinkles  upon  the  contraction 
of  the  spleen. 

If  this  mode  of  reasoning,  derived  from  an  arrangement 
of  parts  which  no  one  denies,  be  correct;  it  follows  that 
physiologists  have  erred  sadly  in  the  supposed  uses  of  the 
omentum  majus.  That  this  organ  is,  in  fact,  only  subsi- 
diary to  the  enlargement  of  the  stomach  and  colon,  so  as 
to  prevent  the  rupture  of  their  peritoneal  coat,  and  that  it 
is  neither  intended  to  keep  the  belly  warm,  as  so  learned  a 
naturalist  as  M.  G.  Cuvier  has  suggested;*  nor  is  it  a spe- 

* XXn.  Legon  D’Anat  Comp. 


OF  THE  OMEIfTA. 


cial  stoi’e-house  for  the  wants  of  the  system  during  the  des- 
titution of  other  aliment,  further  than  adipose  matter  in 
other  parts  of  the  body  is.*  In  regard  to  the  first  theory, 
it  does  not  appear  that  the  inhabitants  of  cold  climates  are 
better  furnished  with  an  omentum  majus  than  those  of  the 
torrid  zone:  that  it  is  better  developed  in  winter  than  it  is 
in  summer;  that  it  is  tucked  up  in  warm  weather  to  cool  the 
intestines,  or  spread  out  in  cold  weather  to  make  them  more 
comfortable.  On  the  contrary,  it  is  ascertained  that  its  po- 
sition is  variable  at  all  seasons;  that  in  the  coldest  of  weather 
it  is  as  often  found  collected  in  the  epigastric  region,  or  to 
one  side  of  the  abdomen,  as  it  is  in  the  warmest;  conse- 
quently its  position  is  the  result  of  whatever  motions  may, 
for  the  time,  have  been  impressed  upon  it  by  the  distention 
of  the  stomach,  and  by  the  peristaltic  movements  of  the 
bowels.  In  regard  to  the  theory  of  Dr.  Rush,  the  objec- 
tion is  insurmountable,  that  children,  who  are  equally,  if 
not  more,  exposed  to  starvation  and  sickness  than  adults; 
never  have  fat,  except  in  very  small  quantities,  in  the 
omentum,,  and  that  only  along  the  course  of  its  vessels. 
The  fat  is,  therefore,  not  to  be  viewed  as  an  essential  cir- 
cumstance in  the  structure  of  the  omentum,  as  all  children 
and  many  adults  have  it  only  very  sparingly : for  the  omentum 
being  wanted  as  a membrane  of  reserve  to  the  stomach  and 
colon,  the  deposite  of  fat  in  it  is  in  obedience  to  one  of  the 
general  laws  of  the  system,  whereby  the  cellular  substance 
beneath  the  serous  membranes  is  disposed  to  secrete  fat  as 
the  individual  advances  in  life;  which  is  exemplified  on  the. 
heart  and  in  the  pleura.  Another  argument  is,  that  in  the 
ruminating  animals,  where  there  are  four  stomachs,  and 
from  the  vegetable  nature  of  their  aliment  these  stomachs 
must,  in  the  course  of  digestion,  be  very  much  distended, 
the  great  omentum  is  of  proportionate  magnitude,  t 

As  in  other  parts  of  the  body  the  fat  of  the  omentem  accu- 
mulates in  animals  that  take  little  exercise,  while  it  is  very 
deficient  in  such  as  lead  an  active  life. 

* An  inquiry  into  the  uses  of  the  omentum,  by  James  Eush,  Philad.  1809. 

j Cuvier,  XXII.  Lecon,  loc.  cit.  - 


ORGANS  OF  DIGESTION. 


i 1 

I am  induced  to  believe  that  the  hard  knots  felt  in  the  ab- 
domen of  such  persons  as  suffer  from  abdominal  affections, 
frequently  depend  upon  the  accumulations  of  the  omentum 
majus,  at  particular  but  variable  points. 


CHAPTER  III. 

OF  THE  CHYLOPOIETIC  VISCERA. 

SECT.  I. OP  THE  STOMACH. 

The  Stomach  ( Ventriculus  Stomachus)  is  a hollow  vis- 
cus,  situated  in  the  epigastric  region,  intended  to  receive  at 
one  end  alimentary  matters  from  the  oesophagus,  and  to 
transmit  them,  at  its  other  extremity,  after  digestion,  into 
the  intestinal  tube.  It  is  a sort  of  conoidal  sac,  curved  con- 
siderably upwards,  and  presents  two  Faces,  two  Orifices,  two 
Curvatures,  and  two  Extremities. 

The  Faces  of  the  stomach  are,  from  their  position  named 
anterior  and  posterior,  or,  one  presents  to  the  spine  and  the 
other  towards  the  linea  alba.  The  flat  configuration  is  rendered 
more  obvious  when  the  organ  is  empty;  for  when  distended 
it  is  rounded,  and  the  anterior  face  is  caused  to  look  forwards 
and  upwards  from  the  resistance  of  the  spine  behind.  In  other 
respects  they  do  not  present  any  thing  worthy  of  particular 
attention. 

The  two  Orifices  of  the  stomach  are  named  Cardia  and  Py- 
lorus. The  first  is  at  the  left  and  most  superior  part,  but  re- 
moved to  the  distance  of  two  inches  or  more  from  the  left 
extremity.  It  is  generally  considered  a smooth  uninterrupted 
continuation  of  the  oesophagus  into  the  stomach,  immediately 
after  the  oesophagus  has  passed  through  the  diaphragm  into 
the  abdomen.  But  in  a preparation  by  me,  Dec.  1828,  made 
by  drying,  and  now  in  the  cabinet  of  the  anatomical  chair,  a 


OF  THE  STOMACH. 


25 


eirculai'  rounded  pad  is  very  perceptible  at  the  cardiac  ori- 
fice; being  elevated  two  lines  or  more  all  around,  so  that  it 
makes  a perfect  ring  of  from  eight  to  twelve  lines  broad  at 
its  base.  This  pad  seems  to  be  formed  of  a substance  sui 
generis,  which  is  almost  perfectly  white,  elastic,  and  con- 
sists of  the  finest  filaments  resembling  carded  cotton:  it  is 
placed  between  the  lining  membrane  of  the  cardiac  orifice 
and  the  adjoining  coat.  The  pylorus,  when  viewed  exter- 
nally, seems  like  a smooth  continuation  of  the  stomach  into 
the  duodenum;  but  when  felt,  there  is  a manifest  thickening 
of  the  part,  depending  upon  a structure  to  be  presently  ex- 
plained. It  points  upwards  and  to  the  left  side,  but  is,  by 
the  whole  thickness  of  the  liver,  lower  down  than  the 
cardia. 

The  two  Curvatures  are  designated  the  great  and  small, 
or  the  upper  and  the  lower.  The  first,  foi’ming  the  upper 
margin  of  the  stomach,  is  bounded  at  its  extremities  by 
the  orifices,  and  is  very  concave;  its  curvature  is  maintained 
both  by  a natural  configuration  and  by  the  small  omentum. 
The  great  curvature  forms  the  whole  inferior  periphery  of 
the  organ,  extending  also  from  one  orifice  to  the  other. 
When  the  stomach  is  flattened,  these  curvatures  form  very 
evident  boundaries  to  the  anterior  and  the  posterior  faces. 

The  Extremities  of  this  organ  are  singularly  dispropor- 
tionate in  size.  That  on  the  left  forms  the  base  of  the 
cone,  or  the  large  extremity,  and  projects  considerably  be- 
yond the  cardia  towards  the  spleen.  It  is  a rounded  cul- 
de-sac,  or  tuberosity,  the  dimensions  of  which  will  of 
course  vary  according  to  the  state  of  distention.  The 
right  extremity,  on  the  contrary,  is  produced  by  a gradual 
diminution  of  the  organ  from  its  middle  to  the  duodenum. 
When  the  stomach  has  approached  within  an  inch  or  two 
of  the  latter,  it  sufiers  a sort  of  constriction,  which  gives 
to  the  right  end  a more  cylindrical  shape.  This  part  is 
sometimes  called  the  little  cul-de-sac,  or  the  antrum  pylori. 

Where  the  stomach  has  been  kept  empty  for  some  time 
previous  to  death,  it  is  found  not  much  larger  than  an  in- 
testine; its  variable  magnitude,  therefore,  prevents  any 
very  rigid  rule  of  dimension  from  being  applied  to  it;  most 


2G 


ORGANS  OP  DIGESTION. 


commonly,  however,  we  find  it  between  the  capaciousness 
of  a pint  and  a quart  measure. 

It  is  retained  in  its  situation  by  its  continuity  with  the 
oesopliagiis  and  duodenum j also  by  the  hepatico-gastric,  and 
the  gastro-splenic  omentum.  It  is  in  contact  above,  at  its 
lesser  curvature,  with  the  diaphragm,  the  left  lobe  of  the 
liver,  and  the  lobulus  spigelii;  at  its  great  extremity  with 
the  spleen,  at  its  posterior  face  with  the  pancreas,  and  at  its 
sjreater  curvature  with  the  colon  and  the  mesocolon. 

The  stomach  is  formed  by  four  laminae  of  a character  es- 
sentially differing  from  each  other:  The  Peritoneal,  the 
Muscular,  the  Nervous,  and  the  Mucous. 

The  Peritoneal  Coat  envelopes  the  stomach  completely, 
and  adheres  closely  except  at  the  curvatures,  where,  as  has 
been  mentioned,  a provision  is  made  for  the  distention  of  the 
organ,  by  the  looseness  and  the  separability  of  the  attach- 
ment of  the  two  laminae  of  the  omentum  minus  and  majus. 
An  uncovered  space  will  consequently  be  found  between 
the  laminae  at  these  places,  along  which  the  vessels  run  that 
furnish  the  stomach.  The  peritoneal  coat  is  very  thin,  and 
is  attached  to  the  subjacent  muscular,  by  very  fine  cellu- 
lar substance,  which  permits  it  to  be  raised  from  the  mus- 
cular by  a careful  dissection. 

The  Muscular  Coat  is  intermediate  in  thickness  to  that 
of  the  intestines  and  of  the  oesophagus,  but  its  fibres  are 
pale,  are  collected  into  flattened  fasciculi,  and  go  in  three 
directions.  The  most  superficial  are  a continuation  of  the 
longitudinal  fibres  of  the  oesophagus,  are  less  numerous, 
and  less  uniform  in  their  distribution,  than  the  circular 
fibres.  The  greater  part  of  them  forms  a flattened  broad 
fasciculus,  which  extends  along  the  lesser  curvature  of  the 
stomach,  from  the  cardiac  to  the  pyloric  orifice.  A thinner 
and  less  distinct  fasciculus  may  be  traced  over  the  great 
cul-de-sac,  and,  somewhat  indistinctly,  along  the  greater 
curvature,  and  a few  others  may  be  seen  on  the  anterior 
and  posterior  faces  of  the  stomach.  The  second  series  con- 
sists in  a lamina  of  circular  fibres  distinctly  covering  the 
whole  surface  of  the  organ.  They  are  not  so  numerous 


OF  THE  STOMACH. 


27 


near  the  cardia,  but  become  more  abundant  as  they  are  exa- 
mined towards  the  pylorus,  in  the  vicinity  *of  which  they 
are  multiplied  so  as  to  form  a lamina  of  two  lines  or  more 
in  thickness.  They  are  parallel  with  each  other,  and,  when 
the  stomach  is  much  distended,  their  fasciculi  separate  so  as 
to  leave  interstices  between  them  in  many  places.  The  in- 
dividual fibres  do  not  surround  entirely  the  stomach,  but  are 
rather  segments  of  circles.  The  third  and  deepest  series  of 
fibres  may  be  called  oblique,  and  are  arranged  into  two  broad 
flattened  fasciculi,  one  of  which  is  placed  to  the  left  side  of  the 
cardia,  and  is  prolonged  over  the  anterior  and  the  posterior 
faces  of  the  stomach;  while  the  other,  being  to  the  right 
of  the  same  orifice,  is  extended  over  the  anterior  and  the 
posterior  faces  of  the  cul-de-sac,  where  it  supplies  the  want 
of  transverse  or  circular  fibres;  they  are  considered  as  a con- 
tinuation of  the  circular  fibres  of  the  oesophagus. 

The  Nervous  Coat  connects  the  muscular  with  the  mu- 
cous. It  is  formed  from  a compact,  thick,  and  short  cellu- 
lar substance,  which  contributes  much  to  the  general  strength 
of  the  organ,  and  serves  to  conduct  the  blood  vessels  and 
the  nerves  to  the  mucous  coat. 

The  Mucous  or  Villous  Coat  is  the  most  internal,  is  not 
quite  a line  in  thickness,  and  can  be  readily  raised  up  by 
dissection.  In  an  undistended  state  of  the  stomach  it  is 
brought  into  a number  of  wrinkles,  which  are  very  irregu- 
lar in  their  form,  size,  and  direction,  and  disappear  imme- 
diately on  inflation,  or  at  least  leave  but  very  faint  traces. 
It  is  continuous  with  the  internal  membrane  of  the  oesopha- 
gus and  of  the  duodenum,  but  presents  a surface  difiering 
from  either  of  them,  and  which  is  rendered  very  apparent 
by  floating  it  in  water.  The  epidermis,  which  is  continued 
along  the  internal  face  of  the  oesophagus,  ceases  around  the 
cardiac  orifice,  and,  by  a slight  maceration,  may  be  raised 
up  and  demonstrated  to  terminate  there. 

This  membrane  or  coat,  the  office  of  which  is  to  secrete 
the  gastric  juice  for  the  digestion  of  articles  of  food,  presents 
a surface  that  resembles  very  much  common  velvet,  from 
whence  the  term  villous  was  applied  to  it.  It  is  very  com- 


2S 


ORGANS  OF  DIGESTION. 


mon  to  find  it,  if  examined  a short  time  after  death,  present- 
ing, particularly  along  the  smaller  curvature  and  at  the  great 
end,  a pink  and  sometimes  a deeper  colour,  produced  by  an 
accumulation  of  blood  in  its  veins  during  the  agonies  of  dis- 
solution, and  probably  caused  in  the  first  instance  by  an  ar- 
rest of  the  pulmonary  circulation. 

The  texture  of  this  membrane  is  soft,  loose,  and  easily 
lacerated.  When  floated  in  water  and  examined  with  a 
magnifying  glass,  it  is  found  to  have  a superficial  honey- 
comb arrangement,  and  to  be  studded  with  a multitude  of 
small  mucous  orifices  not  more  than  the  fiftieth  part  of  a 
line  in  diameter.  In  the  vicinity  of  the  cardiac  and  of  the 
pyloric  orifices,  the  same  arrangement  is  more  obvious  and 
conducts  to  some  small  muciparous  glands,  which  are  more 
or  less  apparent,  and  called  the  glands  of  Brunner. 

At  the  junction  of  the  lesser  extremity  of  the  stomach 
with  the  duodenum,  the  internal  membrane  is  thrown  into 
a circular  duplicature  constituting  the  pyloric  valve,  and 
abridging  the  size  of  the  orifice.  It  is  seen  most  favoura- 
bly in  the  distended  and  dried  state,  and  then  presents  a 
sort  of  septum  not  unlike  the  form  of  the  iris.  Around 
the  external  periphery  of  this  ring,  the  circular  muscular 
fibres  have  a sudden  augmentation  of  numbers,  which  gives 
them,  when  viewed  from  the  duodenum,  the  appearance  of 
a distinct  circular  muscle,  occasionally  called  the  muscle  of 
the  pylorus,  but  it  does  not  exist  in  a state  so  separate  as 
this  name  indicates.  The  opening  of  the  valve  is  general- 
ly circular,  but  sometimes  ovoidal,  and  it  is  sometimes  to 
one  side. 

It  is  very  common  to  find  the  stomach  divided  as  it  were 
into  two  compartments,  by  a contraction  of  its  middle,  re- 
sembling that  of  an  hour  glass.  It  is  said  that  this  occurs 
habitually  during  digestion;  in  my  personal  observations, 
however,  I have  seen  the  stomach  more  frequently  in  this 
state  when  it  contained  nothing,  not  even  air,  than  when 
articles  of  aliment  were  in  it. 

The  stomach  is  extremely  vascular.  Its  arteries,  being 


INTESTINAL  CANAL. 


29 


branches  of  the  Casliac,  are  the  Gastric,  the  Right,  and  the 
Left  Gastro-Epiploic,  and  the  Vasa  Brevia.  The  first  goes 
along  its  lesser  curvature,  the  second  and  the  third  along  its 
greater  curvature,  and  the  last,  from  four  to  six  in  number, 
go  to  its  cul-de-sac.  They  all  approach  it  between  the  la- 
minae of  its  omenta,  and  undergo  many  divisions  and  sub- 
divisions in  the  cellular  coat;  they  at  length  terminate  by 
forming  a very  fine  and  delicate  vascular  arrangement  in 
the  substance  of  the  mucous  membrane,  and  by  being  suc- 
cessfully injected  give  to  the  latter  a thorough  tinge  of  red. 
The  veins  follow  the  course  of  the  arteries,  and  like  them 
have  frequent  anastomoses,  but  are  larger;  they  terminate 
either  directly  or  indirectly  in  the  trunk  of  the  Vena 
Portarum.  The  nerves  of  the  stomach  come  from  the  Par 
Vagum,  and  from  the  semilunar  ganglion  of  the  Sympa- 
thetic. Its  lymphatics  arise  from  both  the  external,  and 
the  internal  surfaces,  and  their  trunks  having  to  pass  first 
of  all  to  the  lymphatic  glands,  situated  along  the  curvatures, 
afterwards  empty  into  the  thoracic  duct. 

SECT.  II. — OP  THE  INTESTINAL  CANAL. 

The  Intestinal  Canal  is  from  thirty  to  thirty-five  feet  in 
length,  and  extends  from  the  pylorus  to  the  anus.  Owing 
pi'incipally  to  a well  marked  difference  in  magnitude,  it  is 
divided  by  anatomists  into  the  small  and  into  the  Large  In- 
testine. 

Of  the  Small  Intestine. 

The  Small  Intestine  {Intestinum  Tenue)  commences  at 
the  pylorus;  and  terminates  in  the  right  iliac  region  by  a 
lateral  aperture  into  the  large  intestine.  It  is  four-fifths  of 
the  length  of  the  whole  canal,  and  consequently  measures 
from  twenty-four  to  twenty-eight  feet.  When  moderately 
distended  its  diameter  is  about  one  inch.  It  retains  from 
one  end  to  the  other  an  uninterrupted  cylindrical  shape, 
with  the  exception  that  if  the  two  ends  be  compared,  the 
Vox.  II.— 5 


30 


ORGANS  OP  DIGESTION. 


upper  \vill  be  found  larger  than  what  is  stated  as  the  medi- 
um measurement,  and  the  lower  smaller;  or,  in  other  words, 
as  the  intestine  decreases  successively  from  above  down- 
wards, it  as  a whole  is  slightly  conoidal,  though  this  dimi- 
nution is  so  gradual  that  it  is  not  perceptible  at  any  given 
point. 

The  Small  Intestine,  like  the  stomach,  consists  of  four 
distinct  coats,  the  peritoneal,  the  muscular,  the  cellular,  and 
the  mucous. 

The  Peritoneal  Coat  is  complete,  and  forms  the  external 
surface.  It  is  continued  afterwards  in  two  laminae  from  the 
intestine  to  the  lumbar  vertebrae,  thereby  constituting  the 
Mesentery.  The  two  laminae,  where  they  depart  from  the 
intestine,  are  loosely  connected  with  each  other,  for  the  pur- 
pose of  allowing  room  for  the  dilatation  of  the  intestine,  on 
the  same  principle  which  is  exemplified  in  regard  to  the  sto- 
mach. 

The  Muscular  Coat  is  next  to  the  peritoneal.  Its  fibres 
are  pale,  and  form  a lamina  not  so  thick  as  common  writing- 
paper.  The  superficial  ones  are  longitudinal,  not  very 
distinct,  and  too  much  separated  to  form  a perfect  coat.  The 
others  all  run  in  a circular  direction,  approaching  to  the 
spiral,  and  are  sufficiently  numerous  to  form  a perfect  coat; 
none  of  them  perform  a complete  circuit  of  the  intestine, 
but  are  rather  segments  of  circles.  This  coat  is  united  to 
the  peritoneal  by  a thin  scattered  cellular  substance. 

The  Cellular  Coat  of  the  small  intestine,  also  called  the 
nervous,  like  that  of  the  stomach,  is  only  a lamina  of  con- 
densed cellular  substance,  which  serves  as  a medium  of 
connexion  between  the  muscular  and  the  mucous  coat:  and 
also  conducts  to  the  latter  the  blood  vessels,  nerves,  and 
lacteals. 

The  Mucous  Coat  is  the  most  internal,  and  when  it  has 
been  cleaned  by  maceration,  exhibits  an  opaque  pearly  co- 
lour. It  is  remarkable  for  having  its  extent  very  consider- 
ably a^lgmented  beyond  that  of  the  other  coats;  by  being 
thrown  into  a great  number  of  permanent  folds,  or  duplica- 
tures,  which  lie  one  upon  another  successively,  like  the  shin- 


INTESTINAL  CANAL. 


31 


gles  upon  the  roof  of  a house.  These  duplicatures  are  the 
Valvulae  Conniventes,  and  are,  for  the  most  part  about  three 
lines  in  breadth.  They  are  either  placed  in  the  direction  of 
the  circumference  of  the  intestine,  or  are  ver)^  slightly  ob- 
lique; they  seldom  go  all  around,  but  are  rather  in  segments 
of  circles,  and  by  being  arranged  successively,  their  ends 
pass  one  another,  or  are  connected  by  slight  elevations.  They 
are  more  numerous  and  broad  in  the  upper  than  in  the  lower 
half  of  the  intestinum  tenue,  and  are  evidently  intended  to 
retard  the  progress  downwards  of  alimentary  matter,  and  to 
increase  the  surface  for  absorption  and  for  exhalation. 

The  mucous  membrane,  on  the  side  which  it  presents  to 
the  cavity  of  the  intestine,  is  furnished  with  a great  num- 
ber of  delicate  cylindrical  projections,  resembling  the  down 
on  the  skin  of  an  unripe  peach,  and  called  Villi,  from 
whence  the  term  villous  has  also  been  applied  to  this  coat. 
These  villi  are  to  be  found  in  abundance  everywhere;  but 
in  the  upper  half  of  the  intestinum  tenue  they  are  so  nume- 
rous as  to  stud  its  whole  surface,  and  to  be  in  contact  with 
each  other.  They  are  from  one-fourth  to  a line  in  length, 
and  some  of  them  when  examined  with  a microscope  ap- 
pear flattened  and  fungiform.  According  to  the  estimate 
of  Meckel,*  where  they  are  thickest,  every  square  inch  of 
intestine  furnishes  about  four  thousand  of  them,  and  by  ex- 
tending this  computation,  with  a proper  allowance  for  di- 
minished numbers  below,  their  aggregate  amount  is  about 
one  million. 

Each  Villus  is  composed  of  an  artery,  a vein,  and  a lym- 
phatic, all  united  by  cellular  substance.  From  the  extreme 
vascularity  of  the  mucous  membrane,  the  blood  vessels 
readily  receive  a fine  injection  and  thereby  become  evi- 
dent, forming  a very  delicate  vascular  network  in  each  of 
the  villi.  It  is  ascertained  that  the  lymphatic  opens  on  its 
surface,  but  whether  by  one  or  more  orifices  is  yet  un- 
settled. According  to  the  celebrated  Lieberkuhn,  there 
is  commonly  but  one  orifice  at  the  end  of  each  villus,  and 
very  rarely  two;  this  assertion  he  considered  himself  as 


* Mamiel  D’Anat. 


OKGAKS  OF  DIGESTION. 


having  established  by  passing  a current  of  air  through  the 
villus  till  it  was  dried,  and  then  slitting  it  open.  Hewson, 
Cruikshank,  and  W.  Hunter,  on  the  contrary,  are  said  to 
have  found  many  more,  amounting  even  to  twenty,  on  such 
villi  as  were  gorged  with  chyle.  The  subject  has  been  fruit- 
ful with  controversy  to  anatomists,  and  ranks  many  distin- 
guished champions  on  each  side;  but  as  from  the  minute- 
ness of  the  parts  under  discussion  and  the  consequent  ne- 
cessity of  microscopical  observations,  it  is  exposed  to  much 
fallacy  and  illusion,  it  cannot  be  satisfactorily  settled, 
though  the  general  analogies  of  papillary  structure  are  in 
favour  of  the  latter  authorities.  The  more  important  fact, 
however,  is  ascertained  by  the  admission  of  all,  that  there 
is  a branch  of  the  lymphatic  system  in  every  villus,  which 
has,  for  its  function,  the  absorption  of  chyle  from  the  cavity 
of  the  intestine. 

An  abundance  of  Mucous  Glands  is  found  deposited  in 
the  cellular  coat  of  the  small  intestine,  between  the  muscu- 
lar and  the  villous;  the  ducts  of  which  open  upon  the  in- 
ternal surface  of  the  latter,  in  the  interstices  of  the  villi, 
and  from  their  smallness  require  the  intestine  to  be  floated 
in  water  and  examined  with  a magnifying  glass,  before  they 
can  be  recognised.  In  order  to  see  the  glands  themselves, 
the  intestine  must  be  cleaned  by  soaking  it  in  water;  it  is 
then  to  be  slit  open  longitudinally  and  held  between  the  eye 
and  the  light,  in  which  case  the  glands  appear  like  little 
points  or  spots  in  the  thickness  of  the  intestine.  They  are 
more  abundant  in  the  beginning  of  the  latter,  decrease  about 
its  middle,  and  increase  again  towards  its  termination. 
Their  structure  is  very  simple,  as  they  consist  in,  a conge- 
ries of  blood  vessels,  terminating  in  short  canals  secreting 
mucus.* 

Some  of  these  glands  are  microscopical,  and  are  called 
cryptse;  others  are  to  be  found  from  that  size  to  a line  in 
diameter,  and  flattened.  They  are  either  alone  or  in  clus- 
ters. The  former  (Glandulae  Solitariae.  Brunneri)  are  found 

' Stcmmei'in^,  de  Covp.  Hum.  Fabrica, 


INTESTINAL  CANAL. 


33 


principally  about  the  duodenum  and  the  neighbouring  por- 
tion of  the  small  intestine.  The  latter  (Glandulae  Agmi- 
natae,  Peyeri)  exist  principally  in  the  lower  part  of  the 
small  intestine,  and  are  collected  into  clusters  varying  from 
a few  lines  to  three  or  four  inches  in  length,  but  seldom 
more  than  eight  or  nine  lines  broad.  All  of  these  mucipa- 
rous glands  are  too  much  flattened  to  project  sensibly  into 
the  cavity  of  the  intestine,  and  when  they  do,  there  is  rea- 
son to  believe  that  .they  are  in  a diseased  state.  They  are 
least  abundant  near  the  mesentery. 

The  Small  Intestine,  though  an  uninterrupted  tube  from 
one  end  to  the  other,  is  divided  by  anatomists  into  Duode- 
num, Jejunum,  and  Ileum.  There  is  some  reason  for  the 
fii’st  name,  but  the  two  latter  may  be  very  conveniently 
blended,  as  has  been  done  by  some,  under  the  term  Me- 
senteric Portion  of  the  intestinal  canal. 

The  Duodenum,  named  from  its  being  about  twelve  in- 
ches, or  twelve  fingers’  breadth  in  length,  is  nearest  to  the 
stomach;  or,  in  other  words,  is  the  commencement  of  the 
canal.  It  is  larger  than  either  of  the  others,  and  is,  more- 
over, susceptible  of  great  dilatation,  whence  it  has  also  been 
called  Ventriculus  Succenturiatus.  Its  direction  is  much 
varied;  beginning  at  the  pylorus  it  first  of  all  passes  upwards 
and  to  the  right  side,  till  it  reaches  the  neck  of  the  gall- 
bladder; it  then  turns  downwards  so  as  to  form  a right 
angle  with  itself,  and  descends  in  front  of  the  right  kidney 
to  the  third  lumbar  vertebra,  being  there  placed  behind  the 
superior  lamina  of  the  transverse  mesocolon.  It  then  forms 
a round  elbow,  crosses  the  spine  obliquely  in  ascending 
from  right  to  left,  and  making  its  appearance  to  the  left 
of  the  second  lumbar  vertebra,  is  there  continued  into  the 
mesenteric  portion  of  intestine. 

The  beginning  of  the  duodenum  is  moveable,  and  has  a 
peritoneal  coat  continued  from  the  lesser  omentum;  the 
descending  and  the  transverse  portions  have  no  proper  pe- 
ritoneal coat,  but  are  only  loosely  fixed  between  the  laminse 
of  the  mesocolon;  the  termination  is  both  moveable  and 


34 


ORGANS  01^  DIGESTION. 


has  a peritoneal  covering,  from  being  at  the  commence- 
ment of  tlie  mesentery. 

From  the  course  assigned  to  the  duodenum,  it  is  evident 
that  it  forms  the  segment  of  a circle,  the  concavity  of  which 
looks  to  the  left  side.  This  concavity  is  occupied  by  the 
head  of  the  pancreas.  The  transverse  portion  crosses  the 
spine  below  the  latter,  and  is  separated  from  it  by  the  su- 
perior mesenteric  artery  and  by  the  vena  portarum;  behind 
it  are  the  crura  of  the  diaphragm,  the  ascending  cava,  and 
the  aorta. 

The  organization  of  the  duodenum  is  the  same  with  that 
of  other  portions  of  the  intestinum  tenue.  Its  peculiarities 
consist  onl)’'  in  a partial  deficiency  of  peritoneal  coat,  and 
in  its  augmented  size.  Its  internal  or  mucous  coat  is  very 
much  tinged  with  bile,  abounds  in  valvulse  conniventes, 
and  about  four  inches  from  the  pylorus  is  marked  by  a 
small  tubercle  or  elevation,  indicative  of  the  orifice  of  the 
biliary  and  of  the  pancreatic  ducts. 

The  Jejunum  and*lleum  form  the  remaining  length  of  the 
small  intestine,  and  have  no  external  marks  of  difference 
from  each  other.  They  are  strung  along  the  mesentery, 
and  in  consequence  of  their  great  length  are  thrown  into 
folds  or  convolutions,  which  give  to  them  a complicated 
appearance.  There  is,  however,  no  difficulty  in  tracing 
them  regularly  from  one  end  to  the  other.  They  occupy 
the  umbilical,  the  hypogastric,  and  a part  of  the  iliac  re- 
gions, and  are  surrounded  by  the  circuit  of  the  colon.  The 
upper  two-fifths  is  the  jejunum,  and  the  lower  three-fifths 
the  ileum.  This  distinction,  originally  introduced  by  Ga- 
len,* from  a supposition  that  the  jejunum  was  more  fre- 
quently found  empty  than  any  other  intestine,  has  no  rigid 
anatomical  support  The  only  difference  between  the  two 
is,  that  the  valvulae  conniventes,  abundant  in  the  whole 
length  of  the  jejunum,  become  less  so  at  the  upper  part  of 
the  ileum,  and  finally  disappear  entirely  towards  its  lower 
extremity.  The  distinction  has  therefore  been  rejected  by 


I’orta),  Anat.  Med- 


INTESTINAL  CANAL. 


35 

the  most  approved  modern  authorities,  such  as  Hailer, 
Soemmering,  Meckel,  and  so  on. 

It  sometimes  happens,  that  the  intestinum  tenue  has  one 
or  more  blind  pouches  appended  to  its  sides  and  opening 
into  its  cavity. 

The  Mesentery  {Mesenteriwn)  is  a process  of  peritone- 
um which  serves,  as  mentioned,  to  connect  the  intestinum 
tenue  to  the  posterior  parietes  of  the  abdomen,  and  extends 
its  connexions  from  the  left  side  of  the  second  lumbar  ver- 
tebra to  the  right  iliac  fossa.  This  attachment, called  the  root, 
is  about  six  inches  in  length;  whereas  its  lower  circumfe- 
rence, which  encloses  the  small  intestine  by  giving  it  a pe- 
ritoneal coat,  is  of  course  the  whole  length  of  the  bowel, 
and  consequently  from  twenty-three  to  twenty-seven  feet  in 
length.  This  expansion  becomes  intelligible  the  moment 
that  the  arrangement  of  the  part  is  inspected,  and  is  some- 
what after  the  manner  of  a ruffle,  except  that  it  is  not  puck- 
ered at  the  root. 

The  two  laminae  of  peritoneum  which  form  the  mesetj- 
tery,  contain  between  them  the  superior  mesenteric  artery, 
and  the  corresponding  portion  of  the  vena  portarum;  an 
abundance  of  lymphatic  or  lacteal  glands  and  vessels;  ra- 
mifications from  the  solar  plexus  of  the  sympathetic  nerve; 
and  a considerable  quantity  of  cellular  and  of  adipose  tis- 
sue. The  superior  lamina  is  continued  directly  into  the 
mesocolon,  and  at  the  place  of  junction  the  transverse  part 
of  the  duodenum  is  very  perceptible  beneath.  The  lower 
lamina  descends  along  the  posterior  pai’ietes  of  the  abdo- 
men, concealing  the  large  blood  vessels  there  and  the  ureters. 

Of  the  Large  Intestine. 

The  Large  Intestine  {Intestinum  Crassuni)  exceeds 
much  in  its  diameter  the  small  intestine,  and  differs  also 
from  it  in  not  being  by  any  means  so  regularly  cylindrical. 
It  commences  at  the  inferior  end  of  the  small  intestine  and 
terminates  at  the  anus,  describing  in  this  course,  as  men- 
tioned, a circle  which  surrounds  two  thirds  of  the  abdomen, 


3(i  ORGANS  OP  DIGESTION. 

and  embraces  the  intestinum  tenue.  Like  the  latter,  though 
only  a continuous  tube,  it  is  divided  into  three  parts;  the 
commencement  of  it,  which  is  below  the  insertion  of  the 
ileum,  and  about  two  inches  in  length,  is  the  Coecum  or  Ca- 
put Coli;  the  remaining  portion,  which  occupies  almost  its 
whole  length,  is  called  the  Colon,  until  it  reaches  the  pel- 
vis, when  the  name  is  converted  into  Rectum. 

The  Mesocolon  is  a reflection  or  duplication  of  perito- 
neum, that  fixes  the  large  intestine  to  the  posterior  parietes 
of  the  abdomen.  This  duplicature  is  not  of  a breadth  so 
uniform  as  the  mesentery,  but  allows  to  the  middle  of  the 
large  intestine  very  considerable  motion,  up  and  down,  ac- 
cording to  the  distention  of  the  stomach,  while  the  lateral 
portions  are  very  much  confined.  For  example,  in  the 
right  iliac  fossa  the  mesocolon  is  so  short  that  the  posterior 
surface  of  the  gut  is  in  contact  with  the  iliac  fascia,  and  ad- 
heres to  it  by  loose  cellular  substance;  in  the  right  and  left 
lumbar  regions  the  bowel  is  immoveably  fixed  in  front  of 
the  kidneys,  but  in  the  space  between  these  two  points,  that 
is  to  say,  where  the  bowel  traverses  the  hypochondriac  and 
the  epigastric  or  umbilical  regions,  the  peritoneal  attach- 
ment, here  called,  from  its  situation,  the  transverse  meso- 
colon, is  so  long  and  loose  that  it  forms  a complete  and 
moveable  septum  between  the  small  intestine  and  the  sto- 
mach. In  the  left  iliac  region,  again,  the  large  intestine, 
after  having  been  bound  down  to  the  left  lumbar,  is  sud- 
denly loosened  by  an  increased  breadth  of  the  mesocolon, 
which  permits  it  to  form  a large  convolution  called  its  sig- 
moid flexure.  The  mesocolon  is  then  continued  into  the 
pelvis  in  front  of  the  sacrum,  first  of  all  a little  to  the  left 
of  the  middle  line  of  the  latter,  and,  as  it  descends,  it  gets 
directly  in  front  of  the  middle  line.  The  portion  of  it  in 
the  pelvis  is  called  mesorectum,  after  the  gut  which  it 
serves  to  attach. 

The  composition  of  the  mesocolon  is  precisely  the  same 
with  that  of  the  mesentery,  though  it  be  not  so  thick;  it 
therefore  consists  in  two  laminae  of  peritoneum,  which  con- 
tain between  them  some  adipose  and  cellular  matter,  along 


INTESTINAL  CANAL. 


37 


with  the  arteries,  the  veins,  the  nerves,  and  the  lymphatic 
vessels,  and  glands  belonging  to  the  large  intestine. 

When  the  large  intestine  is  inflated,  it  is  rendered  very 
obvious  that  it  decreases  in  size  from  its  commencement  to 
the  lower  part  of  the  sigmoid  flexure,  it  then  increases 
again  in  size  just  above  the  anus.  Its  surface  is  arranged 
into  three  series  or  longitudinal  rows  of  projections  sepa- 
rated by  transverse  depressions,  the  whole  corresponding 
with  an  internal  cellular  arrangement,  by  the  latter  surface 
being  the  reverse  of  the  former. 

Its  coats,  like  the  small  intestine,  are  four  in  number;  tlie 
peritoneal,  the  muscular,  the  cellular,  and  the  mucous. 

The  Peritoneal  Coat  prevails  in  its  whole  extent  with  the 
exception  of  the  lower  part  of  the  rectum:  on  the  ascending 
and  the  descending  portions  of  the  bowel,  however,  where 
the  latter  comes  in  contact  with  the  parietes  of  the  abdo- 
men, the  peritoneum  does  not  invest  it  entirely;  but  the 
transverse  portion  or  the  arch,  as  it  is  called,  and  the  sig- 
moid flexure,  are  completely  surrounded. 

The  surface  of  this  intestine  is  studded  with  small  pro- 
jections of  various  lengths,  called  Appendices  Epiploicse, 
which  are  small  duplicatures  of  peritoneum  containing  fat. 

The  Muscular  Coat  is  thin,  like  that  of  the  small  intes- 
tine, and  consists  in  two  orders  of  fibres,  the  longitudinal, 
and  the  transverse  or  circular. 

The  longitudinal  fibres  have  the  peculiarity  of  being  col- 
lected into  three  equidistant,  flattened  fasciculi  or  bands,  of 
about  half  an  inch  in  breadth,  which  begin  by  a common 
point  at  the  extremity  of  the  ccecum,  and  extend  to  the  up- 
per end  of  the  rectum.  One  of  them  is  along  the  line  of 
junction  with  the  mesocolon,  another  anterior,  and  the  third 
inferior.  These  fibres,  being  shorter  than  the  other  coats  of 
the  gut,  have  the  effect  of  puckering  them  into  the  internal 
cellular  condition  alluded  to;  for  when  they  are  cut  through, 
the  intestine  is  much  elongated,  and  its  cells  disappear.  It 
occasionally  happens  that  the  longitudinal  fibres,  instead  of 
being  confined  to  the  bands  alluded  to,  exist  in  considerable 

quantity  over  the  intermediate  spaces;  in  this  case  the  cel- 
VoL.  II.— 6 


3S 


ORGANS  OP  DIGESTION. 


lular  arrangement  is  restricted,  and  in  some  instances  en- 
tirely dispensed  vvithj  of  the  latter,  an  example  is  in  the 
Anatomical  Museum. 

The  circular  muscular  fibres  form  a thin  semi-transparent 
lamina  beneath  the  last,  and  do  not  present  any  peculiarity 
of  interest. 

The  Cellular  Coat  is  a condensed  thin  lamina  of  cellular 
substance,  serving  to  connect  the  muscular  with  the  mucous 
coat,  and  to  conduct  the  blood  vessels  and  nerves  to  their 
terminations  on  the  latter. 

The  Mucous  Coat  lines  smoothly  the  internal  face  of  the 
cellular,  and  has  no  doublings  or  folds,  exclusively  in  it, 
like  the  valvule  conniventes  of  the  small  intestine.  The 
transverse  projections  which  it  makes  between  the  longitu- 
dinal bands,  into  the  cavity  of  the  gut,  and  separating  the 
cells  of  the  large  intestine  from  each  other,  are  not  mere 
duplicatures  of  it  alone,  but  are  also  constituted  by  the  other 
coats. 

Near  its  commencement  this  coat  has  the  fungous  appear- 
ance of  the  stomach,  but  about  the  sigmoid  flexure  it  has  a 
plane,  smooth,  and,  to  a degree,  a polished  surface.  It  has 
but  few  villi,  such  as  exist  in  the  small  intestine;  indeed, 
by  some  anatomists  it  is  denied  that  it  has  any.  Its  mucipa- 
rous glands  and  follicles  are  numerous,  and  when  somewhat 
enlarged,  they  project;  they  are  unusually  conspicuous  about 
the  sigmoid  flexure  and  in  the  rectum.  Its  lacteals  are  not 
abundant. 

Each  division  of  the  large  intestine  has  some  peculiari- 
ties of  structure  and  connexion;  which  may  now  be  at- 
tended to. 

The  Coecum,  or  Caput  Coli,  is  generally  from  an  inch 
and  a half  to  two  inches  long,  has  a rounded  termination  be- 
low and  somewhat  to  the  left,  from  which  proceeds  an  in- 
testinal process,  the  Appendicula  Vermiformis.  The  latter 
is  from  three  to  four  inches  long,  is  cylindrical,  has  a dia- 
meter of  two  or  three  lines,  and  consists  also  of  the  same 
number  of  coats,  having  the  same  structure  with  other 


INTESTINAL  CANAL. 


39 


portions  of  the  intestinal  canal;  its  base  is  the  point  from 
which  the  three  longitudinal  bands  start.  It  is  attached  by 
a narrow  duplicature  of  peritoneum,  a process  of  the  me- 
sentery, which  permits  it  to  float  loosely  in  the  abdomen. 
It  seldom  contains  faeces,  but  is  kept  distended  by  flatus. 

The  ccecum,  as  mentioned,  is  for  the  most  part  confined 
to  the  right  iliac  fossa,  but  we  very  frequently  see  it  with 
a length  of  peritoneal  attachment  permitting  it  to  descend 
for  a short  distance  into  the  pelvis. 

The  Ileo-colic  Valve  ( Valvula  Bauhini)  is  formed  at 
the  junction  of  the  ileum  with  the  caput  coli.  This  valve, 
destined  to  prevent  the  return  of  faecal  matter  from  the 
large  into  the  small  intestine,  consists  in  a transverse  ellip- 
tical opening,  or  slit,  whose  lips  become  approximated  in 
the  distentions  of  the  colon.  The  ileum  runs  into  the  left 
wall  of  the  large  intestine,  and  continues  its  cellular  and 
mucous  coats  into  the  corresponding  coats  of  the  latter.  The 
circular  muscular  fibres  of  the  large  intestine  separate  to  a 
certain  degree  to  permit  this  introduction,  but  their  further 
separation  is  restrained  at  each  commissure  or  corner  of  the 
lips,  by  a blending  of  the  structure,  aided  by  a few  liga- 
mentous fibres,  designated  as  the  retinacula  of  Bauhin  or 
of  Morgagni;  ivhich,  however,  are  frequently  not  very  dis- 
tinct. The  lips  themselves,  formed  principally  by  the  mu- 
cous membrane,  approach  one  another  after  the  manner  of 
the  ship  dock  or  hydraulic  gate;  the  superior  is  somewhat 
broader  than  the  inferior.  Their  power  as  well  as  their 
existence  depend  entirely  on  the  tension  which  is  kept  up 
by  the  natural  connexions  of  the  parts;  for  a very  slight  dis- 
section causes  them  to  become  almost  effaced,  and,  instead 
of  forming  an  elliptical  transverse  opening,  to  be  converted 
into  a round  patulous  one. 

The  Colon,  properly  speaking,  has  some  regional  dis- 
tinctions which  are  serviceable  to  accurate  description.  The 
right  lumbar  colon,  which  is  bordered  in  front  by  the  small 
intestine  and  behind  by  the  right  kidney,  extends  from  the 


40 


ORGANS  OF  DIGESTION. 


ileo-colic  valve,  to  the  margin  of  the  false  ribs  of  the  cor- 
responding  side.  The  transverse  colon,  bordered  above  by 
the  stomach  and  below  by  the  small  intestine,  goes  from 
one  hypochondriac  region  to  the  other.  It  is  generally 
found  more  distended  than  the  other  portions.  The  left  lum- 
bar colon  descends  from  the  hypochondriac  region  of  the 
left  side  to  the  sigmoid  flexure,  being  bordered  behind  by 
llie  left  kidney  and  in  front  by  the  small  intestine.  The  sig- 
moid flexure,  placed  in  the  left  iliac  fossa,  forms  a convo- 
lution but  very  indifferently  described  by  the  term  applied 
to  it.  It  is  occasionally  very  long  and  loose,  and  termi- 
nates at  the  left  sacro-iliac  symphysis.  It  is  not  unfre- 
quently  found  destitute  of  the  partitions  which  prevail  in 
other  parts. 

The  Rectum  begins  at  the  left  sacro-iliac  symphysis,  and 
passes  obliquely  downwards  to  the  centre  of  the  sacrum, 
thence  in  front  of  the  middle  line  of  the  sacrum,  and  of 
the  coccyx,  to  terminate  at  the  point  of  the  latter.  It  is 
not  regularly  cylindrical,  but,  just  above  the  anus,  is  dilated 
into  a wide  pouch,  flattened  from  before  backwards  by  the 
pressure  of  the  bladder,  and  very  distinguishable  upon  the 
introduction  of  the  finger,  for  it  is  but  seldom  in  a contract- 
ed state.  It  of  course  has  a flexure  in  it  adapting  itself  to 
the  concavity  of  the  sacrum,  and  is  bounded  in  front  by  the 
bladder,  the  prostate  gland  and  the  vesiculse  seminales  of 
the  male,  and  by  the  vagina  and  the  uterus  of  the  female. 

The  peritoneum  covers  only  the  superior  two-thirds  of 
the  rectum,  and  attaches  it,  by  the  short  duplicature  called 
the  mesorectum,  to  the  front  of  the  sacrum.  A small  pouch, 
passing  down  between  the  vesiculae  seminales  almost  to  the 
base  of  the  prostate,  is  formed  by  the  peritoneum  in  its 
course  from  the  rectum  to  the  bladder. 

The  muscular  coat  of  the  rectum  has  a thickness  and  red- 
ness surpassing  much  that  of  any  other  intestine-,  and  is  di- 
vided very  clearly  into  two  laminae,  the  external  of  which 
consists  in  longitudinal  and  the  internal  in  circular  fibres. 
The  external  forms  in  itself  a complete  coat  continuous  with 


aENEEAL  ANATOMY  OF  THE  MUCOUS  MEMBRANES.  41 

the  longitudinal  bands  of  the  colon,  but  is  much  increased 
by  additional  fibres.  The  circular  fibres  also  form  a com- 
plete coat,  and,  just  below  the  pouch  of  the  rectum,  are 
multiplied  so  much  for  eight  or  ten  lines  as  to  be  a perfect 
internal  sphincter  muscle,  bearing  a strong  analogy  with 
the  pyloric  muscle  of  the  stomach.  At  the  anus,  an  ar- 
rangement of  the  muscular  coat  prevails,  which,  as  far  as  I 
know,  has  not  been  heretofore  attended  to  by  anatomists. 
The  longitudinal  fibres,  having  got  to  the  lower  margin 
of  the  internal  sphincter,  turn  under  this  margin  between 
it  and  the  external  sphincter,  and  then  ascend  upwards 
for  an  inch  or  two  in  contact  with  the  mucous  coat,  into 
which  they  are  finally  inserted.  This  connexion  must 
have  obviously  much  influence  in  the  protrusions  of  the  mu- 
cous coat,  which  sometimes  take  place. 

The  mucous  coat  of  the  rectum  is  thick,  red,  and  fun- 
gous, and  abounds  in  mucous  lacunae  and  glands. . It  is 
smoothly  laid  above,  but  below  it  is  thrown  into  superficial 
longitudinal  folds  called  columns.  The  wrinkling  of  the 
anus  is  from  the  influence  of  the  external  sphincter  ani  mus- 
cle. In  some  subjects  large  cells  are  formed  in  the  cavity 
of  the  rectum  by  transverse  doublings  of  the  mucous  coat 
only,  resembling  the  valvulae  conniventes  of  the  small  in- 
testine; this,  however,  is  not  the  most  frequent  arrange- 
ment, though  deserving  of  notice. 

The  large  intestine  is  supplied  with  blood  from  a part  of 
the  superior  mesenteric,  from  the  whole  of  the  inferior  me- 
senteric, and  from  the  internal  pudic  artery.  Its  veins 
empty  into  the  vena  portarum.  Its  nerves  are  derived 
from  the  solar  and  the  hypogastric  plexus  of  the  sympa- 
thetic. 

SECT.  in. — OF  THE  GENERAL  ANATOBIY  OF  THE  MUCOUS 
BIEBIBRANES. 

The  extent  of  the  mucous  coat  of  the  alimentary  canal, 
and  the  important  and  varied  sympathies  which  it  has  with 
most  other  parts  of  the  body,  render  useful  some  remarks 


43 


ORGANS  OF  DIGESTION. 


on  membranes  of  this  kind  generally.  Mucous  Membranes 
are  so  called  from  the  nature  of  the  secretion  which  they 
furnish:  and  the  term  having  been  first  applied  to  the  lining 
coat  of  the  nose,  a similitude  of  character  has  caused  its  ex- 
tension to  that  of  other  organs.  The  celebrated  Bichat,  the 
founder  of  the  science  of  general  anatomy,  was  the  first  to 
adopt  fully,  and  to  perceive  the  value  of  this  classification; 
since  which  it  has  been  almost  universally  received  by  ana- 
tomists. 

As  the  skin  forms  an  external  covering  to  the  body,  so 
mucous  membrane  lines  the  internal  surface  of  the  hollow 
viscera.  When  it  is  recollected  that  this  membrane  forms 
an  internal  tegument  to  the  whole  alimentary  canal,  from 
the  mouth  to  the  anus;  to  all  of  the  urinary  and  genital  ap- 
paratus; to  the  whole  respiratory  system,  from  the  nose 
down  the  trachea  and  throughout  the  lungs;  it  will  be  ad- 
mitted'that  in  its  extension  it  exceeds  much  that  of  the  skin. 

A mucous  membrane  presents  two  surfaces,  one  of  which 
adheres  to  the  contiguous  parts,  and  the  other  is  free  by 
being  internal.  The  adherent  surface  is  attached  by  a cel- 
lular structure  somewhat  condensed.  This  cellular  struc- 
ture is  principally  remarkable  for  its  want  of  disposition  to 
secrete  fat  into  its  interstices;  a property  of  immense  im- 
portance, as  without  it,  obstructions  would  be  continually 
occurring  to  the  destruction  of  life:  it  is  pervaded  by  a mul- 
titude of  fine  vessels  and  nerves,  running  forward  to  be  spent 
upon  the  mucous  membrane;  and  has  been  unfortunately 
named  nervous  coat,  by  anatomists  of  high  authority.  The 
strength  of  attachment  which  it  furnishes  is  somewhat  va- 
ried; for  example,  in  the  small  intestinal  canal  I have  of- 
ten seen  the  mucous  membrane  caught  at  one  end  and  en- 
tirely withdrawn  from  the  other  coats,  an  experiment  which 
alone  can  give  rigid  ideas  of  its  greater  length,  as  by  it  all 
the  duplicatures  or  valvulse  conniventes  are  stretched  out. 
The  experiment  succeeds  much  more  certainly  by  the  regu- 
lar pressure  of  a column  of  water  between  the  tunics  of  the 
intestine.  The  mucous  membrane  of  most  organs  is  arranged 
into  wrinkles  and  duplicatures,  for  the  purpose  of  augment- 


(lENERAL  ANATOMY  OP  THE  MUCOUS  MEMBRANES.  43 

ing  its  extent.  This  arrangement  prevails  in  the  nose, 
and,  as  mentioned,  in  the  ossophagus,  in  the  stomach  and 
intestines;  to  say  nothing  of  many  other  instances  Avhich 
are  noticed  in  the  description  of  each  organ.  In  some  ex- 
amples they  are  permanent,  and  in  others  depend  on  the 
state  of  contraction  of  an  exterior  muscular  coat.  The  in- 
terior face  of  the  mucous  membranes,  allowance  being  made 
for  the  inequalities  just  stated,  moreover  presents,  when 
closely  viewed,  an  abundance  of  more  minute  depressions 
and  of  elevations,  causing  it  to  resemble  velvet.  Some  of 
these  depressions  are  so  large  as  to  give  it  a cellular  ap- 
pearance, as  in  many  parts  of  the  intestinal  canal,  and  the 
gall-bladder,  and  have  been  particularly  described  by  Sir 
Everard  Home. 

In  regard  to  organization,  the  mucous  membranes  are  of 
a soft,  spongy  consistence;  easily  yield  to  mechanical  vio- 
lence; and  depend  for  their  strength  upon  the  surrounding 
cellular  coat.  They  are  not  of  a uniform  thickness;  for 
example,  they  are  much  thinner  in  the  urinary  and  genital 
apparatus,  than  in  the  alimentary  canal;  they  also  present 
some  varieties  of  consistence.  They  yield  very  readily  to 
putrefaction,  and  are  quickly  reduced  to  a pulpy  state  by 
the  action  of  the  mineral  acids.  Caustics  of  all  kinds  act 
more  promptly  on  them  than  on  the  skin,  owing  to  the 
protection  of  the  latter  by  the  epidermis;  Bichat  states, 
that  in  the  practice  of  the  Hotel  Dieu,  this  effect  is  fre- 
quently exemplified,  by  the  administration  of  lunar  caustic 
among  the  common  people  for  the  purpose  of  poisoning. 
The  nitric  acid  leaving  the  silver,  quickly  applies  itself  to 
the  mucous  membrane  of  the  stomach,  and  disorganizing  it, 
forms  a whitish  eschar,  which,  if  life  is  preserved  long 
enough,  is  finally  detached  in  a membranous  form. 

One  of  the  remarkable  properties  of  the  mucous  surfaces 
of  the  stomach  and  intestines  is,  that  of  coagulating  milk. 
According  to  the  experiments  of  Spallanzani,  the  gastric 
juice,  in  the  living  state,  assists  in  this  change;  but  it  is 
perfectly  well  known  in  domestic  affairs,  that  the  dried 


44 


OBftANS  OF  DIGESTION. 


stomach  of  a calf,  where  the  juices  have  been  completely 
evaporated,  is  also  productive  of  it.  The  observations  of 
the  same  author  led  him  to  conclude,  that  the  peritoneal  and 
the  muscular  tunics  of  the  stomach  are  insufficient  to  pro- 
duce this  effect. 

The  internal  surface  of  all  the  mucous  membranes  is  fur- 
nished with  small  projecting  points  or  spiculse,  called  pa- 
pillae or  villi.  They  are  particularly  conspicuous  and  nu- 
merous, as  mentioned,  on  the  upper  surface  of  the  tongue 
and  in  the  small  intestine,  and  bear  an  analogy  of  function 
and  organization  with  the  very  fine  papillae  which  are  seert' 
every  where  on  the  surface  of  the  cutis  vera.  It  is  to  be 
remembered  that  in  the  stomach  their  organization  is  suited 
to  the  secretion  of  gastric  juice,  and  that  in  the  intestines 
the  origin  of  the  lacteals  is  interwoven  with  them.  These 
papillae  are  every  where  furnished  with  nervous  filaments, 
giving  them  a high  degree  of  sensibility;  and  with  an  abun- 
dance of  blood  vessels.  The  term  papillae  has  been  more 
exclusively  applied  to  the  projections  on  the  surface  of  the 
tongue,  from  their  greater  size;  they  are  there  also  more 
distinctly  covered  with  an  epidermis,  frequently  called  epi- 
thelium. The  villi,  from  their  connexion  with  the  process 
of  digestion,  have  been  emphatically  denominated  the  roots 
of  animals.  Accoi’ding  to  M.  Bedard,*  who  has  examined 
them  upon  a plan  of  his  own  contrivance  well  suited  to  ac- 
curate microscopal  observation,  they  are  presented  under  a 
diversity  of  shapes.  Those  of  the  pyloric  half  of  the  sto- 
mach and  of  the  duodenum  being  broader  than  they  are 
long,  are  composed  of  very  small  thin  laminae,  having  a 
tufted  arrangement.  Those  of  the  jejunum  are  long  and 
narrow,  having  more  the  form  commonly  assigned  to  them, 
while  in  the  lower  part  of  the  ileum  and  in  the  colon  they 
again  become  laminated. 

It  should  be  observed  that  notwithstanding  the  assertion 
of  Lewenhoeck,  Hewson,  Hunter,  and  others,  the  fact  is 
still  called  in  question,  by  two  of  the  most  distinguished 
anatomists  of  the  present  time,  MM.  Bedard  and  J.  F. 


Anat.  Gen.  p.  253. 


GENERAL  ANATOMY  OF  THE  MUCOUS  MEMBRANES.  45 

Meckel,  whether  the  orifices  of  the  lacteals  are,  under  any 
circumstances,  visible  on  the  surface  of  the  villi.  Admit- 
ting  that  they  do  not  open  as  stated,  the  power  of  intersti- 
tial absorption  in  the  mucous  membrane  will  still  account 
for  the  chyle  finally  getting  into  the  lacteals,  as  well  as  for 
fluids  getting  into  the  circulation  from  the  stomach,  when 
its  continuity  with  the  intestinal  canal  has  been  interrupted. 

The  Epidermis  or  Epithelium  of  mucous  membranes  is 
very  distinct  at  their  external  orifices,  but  becomes  less  and 
less  apparent  towards  the  interior  of  the  body,  until  finally 
it  cannot  be  seen  at  all;  and  the  probability  is  that  it  is  en- 
tirely deficient,  notwithstanding  the  assertion  of  Haller 
to  the  contrary.  A pathological  proof  may  be  brought  to 
our  aid  in  settling  this  question.  It  is  a matter  of  common 
observation,  that  when  the  interior  of  mucous  membranes 
is  exposed  by  an  eversion  for  a long  time,  to  the  action  of 
the  atmosphere,  they  take  on  more  of  the  structure  of  skin, 
and  become  evidently  covered  with  a cuticle  which  pro- 
tects them  and  diminishes  their  secretion.  This  is  exem- 
plified in  eversion  of  the  vagina  from  prolapsed  uterus,  in 
elongated  and  tumid  labia  interna,  and  in  other  ways;  re- 
store the  parts  to  their  natural  situation,  and  they  are 
brought  back  to  their  oi'iginal  structure.  In  the  partial 
prolapse  of  the  mucous  membrane  of  the  rectum,  from 
piles,  corresponding  circumstances  occur.  From  this  we 
infer,  that  the  development  of  cuticle  depends  very  much 
upon  the  degree  of  exposure  which  any  surface  of  the  body 
has  to  undergo.  The  reverse  also  takes  place:  shut  up 
or  close  any  surface  of  the  skin  so  that  it  is  put  on  the  foot- 
ing of  an  interior  cavity,  and  it  immediately  begins  to  as- 
similate itself  to  a mucous  membrane.  This  is  proved  by 
the  tendency  in  young  children  to  a detachment  of  the  cu- 
ticle, or  excoriation  of  the  opposed  surfaces  of  the  deep 
wrinkles  about  their  thighs  and  in  their  perineum;  a ten- 
dency obviated  by  the  habit  of  nurses  of  covering  these 
surfaces  with  powdered  starch.  It  is  also  manifested  fre- 
quently in  the  dressing  of  wounds  with  sticking  plaster, 
where  an  incautious  approximation  of  the  contiguous  sur- 
faces of  skin,  not  only  is  followed  by  excoriation,  but  even 
Voi.  II.— -7 


•l(j 


OKGANS  01'  DIGESTION. 


by  ulceration;  a fact,  the  importance  of  which  used  to  be 
set  in  proper  relief  by  Dr.  Physick  in  his  surgical  lectures, 
and  of  which  I have  seen  an  example  in  a case  of  extirpa- 
ted female  mamma. 

The  mucous  membranes  vary  in  colour  from  a very  light 
pink  to  a deep  red,  which  is  owing  to  the  blood  that  circu- 
lates in  them.  In  cases  of  suffocation  they  become  almost 
brown  from  the  congestion  of  blood  in  them,  while  in  fainting 
they  turn  white  from  the  desertion  of  the  latter.  These  ves- 
sels, after  having  penetrated  the  thickness  of  the  membrane, 
ramify  with  extreme  minuteness  on  its  surface.  In  conse- 
quence of  this  superficial  situation,  the  vessels  being  unsup- 
ported on  one  side,  are  exposed  to  rupture  from  slight  con- 
cussions; in  this  way  hemorrhage  is  produced  in  the  lungs 
from  coughing,  and  bleeding  at  the  nose  from  blows  upon 
the  head. 

Exhalent  vessels  exist  in  great  numbers  in  the  mucous 
membranes;  this  is  especially  the  case  in  the  lungs,  where 
the  pulmonary  perspiration,  as  it  is  called,  is  very  obvious 
to  common  observation.  Elsewhere,  this  discharge  is  so 
much  blended  with  the  mucus  of  the  part  that  it  is  difficult 
to  appreciate  its  quantity.  From  the  superficial  situation 
of  the  blood  vessels,  it  is  clear  that  the  exhalent  orifices  or 
pores,  have  but  a short  course  to  run.  This  is  considered 
by  Bichat  as  a satisfactory  reason  for  the  tendency  of  the 
blood  to  escape  through  them,  or  to  ooze  out  where  there 
is  no  rupture. 

Absorbents  exist  also  in  great  numbers,  as  proved  by  the 
absorption  of  chyle,  of  watery  drinks  from  the  intestinal  ca- 
nal; and  by  the  inhalation  of  the  vapour  of  spirits  of  turpen- 
tine into  the  lungs,  rapidly  communicating  the  particular 
smell  of  this  article  to  the  urine.  There  are,  moreover, 
cases  recorded  of  obstructed  urethra,  where  the  urine  has 
been  almost  entirely  absorbed  by  the  mucous  coat  of  the 
bladder. 

In  regard  to  nerves,  the  mucous  membranes  are  well  fur- 
nished with  them.  Bichat  has  remarked  that,  wherever 


GENERAL  ANATOMY  OP  THE  MUCOUS  MEMBRANES.  47 

these  membranes  are  situated  near  the  surface  of  the  body 
and  enjoy  common  sensibility,  they  are  almost  wholly  fur- 
nished from  the  central  portions  of  the  nervous  system ; this 
is  exemplified  in  the  conjunctiva,  the  pituitary  membrane, 
the  palate,  the  glans  penis,  &c.  On  the  contrary,  the  sym- 
pathetic nerve  f^urnishes  the  intestines,  the  bladder,  and  the 
excretory  tubes  generally. 

Mucous  Glands,  as  they  are  called,  exist  throughout  the 
system  of  mucous  membranes,  being  situated  either  under 
them  or  in  their  thicknesses.  From  them  is  derived  the 
mucilaginous  fluid  which  lubricates  so  abundantly  their  in- 
terior surfaces,  so  as  to  facilitate  the  passage  of  extraneous 
bodies,  and,  at  the  same  time,  to  protect  the  membrane 
from  mechanical  violence.  These  glands  are  of  various 
sizes,  from  that  of  the  tonsils  and  the  muciparous  glands 
on  the  lips,  cheeks,  and  root  of  the  tongue,  to  the  almost 
imperceptible  cryptac  of  the  bladder  and  urethra.  Their 
shape  is  either  lenticular,  rounded,  or  that  of  a pouch.  The 
two  former  have  their  parietes  of  a sensible  thickness,  but 
the  last  are  too  thin  to  be  distinguished  from  the  mucous 
membrane  itself.  For  the  most  part  the  excretory  duct  of 
these  glands  is  short  and  patulous,  so  as  to  lead  directly  into 
the  substance  of  the  gland.  This  is  remarkably  the  case 
with  the  tonsils,  which  consist  in  a congeries  of  these  folli- 
cles; and  with  the  glands  on  the  root  of  the  tongue.  In 
some  animals  they  are  so  numerous  as  to  form  almost  a dis- 
tinct lamina  to  the  intestines;  after  the  manner  of  the  human 
subject,  on  the  palate  and  parietes  of  the  mouth. 

The  Mucosity  discharged  from  these  glands  is  one  of  the 
principles  of  animals,  and,  as  is  well  known,  exists  also  to 
a great  extent  in  some  vegetables.  When  perfectly  pure 
and  fluid,  it  is  white,  transparent,  inodorous,  and  insipid. 
It  is  insoluble  in  alcohol,  but  soluble  in  acids.  Water  forms 
more  than  nine  tenths  of  it,  the  remainder  is  mucus,  pro- 
perly speaking,  blended  with  some  neutral  salts  of  soda  and 
potash. 

The  mucous  membranes  are  exposed  to  a multitude  of 
morbid  alterations,  such  as  polypus,  scirrhus,  cancer,  phleg- 


48 


ORGANS  OP  DIGESTION. 


morrhagise  or  serous  fluxes,  blenorrhagiae  or  mucous  fluxes, 
inflammation  in  all  its  forms,  gangrene,  ulcerations,  and 
congestions. 


CHAPTER  IV. 

OF  THE  ASSISTANT  CHYLOPOIETIC  VISCERA. 

SECT.  I. OP  THE  LIVER. 

The  Liver  {Hepar,  Jecur)  is  the  largest  glandular  body 
in  the  human  frame.  It,  as  mentioned,  occupies  the  whole 
of  the  right  hypochondriac  region,  the  upper  half  of  the  epi- 
gastric, and,  as  it  becomes  thinner  in  going  towards  the  left 
side,  it  occupies  a small  space  in  the  right  superior  part  of 
the  left  hypochondriac  region.  Its  whole  superior  face  is 
in  contact  with  the  diaphragm;  on  the  left  it  is  bounded  by 
the  spleen,  and  below  by  the  stomach  and  the  transverse 
colon;  behind  it,  are  the  vertebral  column  and  the  ascend- 
ing cava. 

The  shape  of  the  liver  is  like  one  half  of  an  ovoidal  body 
cut  into  two  in  the  direction  of  its  long  diameter,  and  having 
the  thick  end  turned  to  the  right  side.  It  is  about  ten 
inches  in  length  by  six  or  seven  wide,  and  weighs  from  four 
to  five  pounds  in  the  adult.  Its  colour  is  a reddish  brown, 
generally,  though,  on  its  under  surface  and  about  its  edges, 
broad  blue  or  black  patches  are  constantly  met  with,  which 
do  not  indicate  any  morbid  derangement. 

Its  upper  surface  is  of  a uniform  convexity,  rather  more 
prominent  at  the  right  posterior  part  than  elsewhere;  ad- 
justs itself  accurately  into  the  concavity  made  by  the  under 
surface  of  the  diaphragm;  and  is  unequally  divided  from  be- 
fore backwards  by  tbe  suspensory  ligament.  The  anterior 
margin  is  thin,  and  is  notched  where  the  suspensory  liga- 


THE  LIVER. 


49 


ment  begins;  the  posterior  margin  is  much  thicker,  and  has 
near  its  middle  a broad  depression,  to  fit  it  to  the  projection 
of  the  vertebral  column.  The  ascending  vena  cava  forms  a 
superficial  sulcus  upon  this  margin,  and  frequently  there  is 
a complete  canal  through  the  substance  of  the  liver  for 
transmitting  it.  The  right  extremity  is  very  thick,  and 
almost  fills  the  hypochondriac  region  of  that  side,  while  the 
left  extremity  is  reduced  to  a thin,  tapering,  and  flexible 
edge. 

The  under  surface  of  the  liver  is  much  more  irregular  than 
the  upper;  it  is  traversed  in  an  antero  posterior  direction, 
in  a line  corresponding  with  the  attachment  above  of  the  sus- 
pensory ligament,  by  the  umbilical  fissure,  (Sulcus  Umbili- 
calis)  which  extends  from  the  notch  in  the  front  edge  to  the 
depression  behind,  and  obtains  its  name  from  having  accom- 
modated in  the  foetal  state,  the  umbilical  vein,  now  convert- 
ed into  a round  ligamentous  cord.  In  the  posterior  part  of 
this  fissure  is  likewise  to  be  seen,  in  the  same  condition, 
what  remains  of  the  ductus  venosus.  The  anterior  portion 
of  the  umbilical  fissure  is  not  unfrequently  converted  into  a 
complete  canal,  by  a portion  of  hepatic  substance  crossing  it 
like  a small  bridge.  The  transverse  fissure  (Sulcus  Trans- 
versus,  Intermedius)  is  situated  in  the  middle  of  the  under 
surface  of  the  liver,  and  extends  along  a third  or  a fourth  of 
the  long  diameter  of  the  latter.  It  begins  somewhat  to  the 
left  of  the  umbilical  fissure,  and,  crossing  it  at  right  an- 
gles, proceeds  towards  the  right  extremity.  It  contains  the 
vena  portarum,  the  hepatic  artery,  and  the  hepatic  duct;  all 
of  which,  are  bound  to  each  other  by  a close  cellular  sub- 
stance. 

The  suspensory  ligament  above,  and  the  umbilical  fissui'e 
below,  give  occasion  to  divide  the  liver  into  Lobes;  right, 
and  left;  of  which  the  right  is  by  much  the  largest,  and  ac- 
commodates almost  entirely  the  transverse  fissure,  having 
also  on  its  under  surface  some  subordinate  elevations,  to  wit, 
the  Lobulus  Spigelii  and  the  Lobulus  Quartus,  together  with 
the  Gall-Bladder. 

The  Lobulus  Spigelii  is  placed  between  the  transverse  fis- 


50 


ORGANS  or  DIGESTION. 


sure  and  the  posterior  margin  of  the  liver,  to  the  right  of  the 
posterior  end  of  the  umbilical  fissure.  Its  shape  is  somewhat 
prismatic,  bifurcating  in  front;  one  of  the  elongations  is  a 
papilla  overhanging  the  transverse  fissure,  and  is  therefore 
considered  as  one  side  of  the  gateway  (porta)  opened  for  the 
vena  portarum;  the  other  elongation  is  a small  ridge,  some- 
times called  Lobulus  Caudatus,  and  is  lost  gradually  on  the 
under  surface  of  the  great  lobe,  by  inclining  to  the  right. 

The  Lobulus  Quartus,  Anonymus,  not  by  any  means  so 
elevated  as  the  last,  but  having  a flattened  surface,  is  placed 
in  front  of  the  transverse  fissure,  between  the  fore  end  of  the 
umbilical  fissure  and  the  gall-bladder;  its  posterior  extremity 
is  the  second  porta  of  the  Liver,  and  is  just  opposite  that  fur- 
nished by  the  Lobulus  Spigelii. 

Theliver,  from  being  completely  enveloped  in  peritoneum, 
has  a smooth  glossy  appearance.  The  reflections  of  this 
membrane,  from  it  to  the  parietes  of  the  abdomen,  form  the 
ligaments  as  they  are  called,  which  consist  each  of  two 
laminae.  The  Falciform  Ligament,  or  Suspensory,  contain- 
ing in  its  anterior  margin  the  remains  of  the  umbilical  vein, 
now  called  Ligamentum  Teres,  begins  at  the  umbilicus,  ex- 
tends from  it  along  the  linea  alba  and  the  middle  line  of  the 
diaphragm,  and,  as  mentioned,  is  reflected  to  the  upper  sur- 
face of  the  liver,  from  the  anterior  to  the  posterior  margin. 
The  Right  Lateral  Ligament  is  situated  behind,  and  departs 
from  the  back  part  of  the  diaphragm  to  the  posterior  margin 
of  the  right  lobe.  The  Left  Lateral  Ligament  also  goes  from 
the  back  part  of  the  diaphragm,  and  is  attached  along  the 
posterior  margin  of  the  left  lobe.  Where  the  suspensory  liga- 
ment inclines  on  each  side  into  the  lateral,  it  passes  with  so 
much  obliquity  as  to  leave  some  portion  of  the  posterior  mar- 
gin of  the  liver  uncovered  by  pei’itoneum;  the  latter,  where 
it  describes  the  periphery  of  this  space,  has  been  rather  un- 
necessarily designated  as  the  Coronary  Ligament. 

In  addition  to  the  peritoneal  coat,  the  liver  has  another, 
connecting  it  with  the  peritoneum,  and  seeming  to  be  only 
condensed  cellular  substance,  which  also  penetrates  into  the 
substance  of  the  gland,  and  holds  its  constituent  parts  toge- 


THE  LIVER. 


51 


ther.  It  is  particularly  well  seen  within  the  circle  of  the 
coronary  ligament. 

Of  the  Organization  of  the  Liver. 

The  Liver,  besides  its  glandular  substance,  is  extremely 
vascular,  and  is  formed  principally  by  the  ramifications  of 
three  kinds  of  blood  vessels,  the  Vena  Portarum,  the  Hepatic 
Artery,  and  the  Hepatic  Veins.  The  two  first  convey  the 
blood  to  it,  and  the  third  removes  it  again,  into  the  general 
circulation,  by  emptying  into  the  ascending  vena  cava.  There 
are  also  branches  of  the  hepatic  duct,  lymphatic  vessels,  and 
nerves. 

The  glandular  substance  is  fragile  and  easily  lacerated; 
when  torn  it  assumes  the  appearance  of  a congeries  of  sphe- 
rical or  polyedrical  grains,  (acini,)  united  in  mass  by  the 
elongations  of  the  cellular  coat,  and  traversed  by  the  trunks 
of  the  blood  vessels.  Each  of  these  granulations  is  about 
the  size  of  a millet  seed,  and  is  a representative  of  the  en- 
tire gland,  as  its  structure  is  complete  in  itself,  being  formed 
by  the  terminations  of  the  blood  vessels,  and  by  the  origin 
of  a branch  of  the  hepatic  duct,  called  the  porus  biliarius. 
When  examined  with  a microscope,  it  is  said  that  those 
acini  are  composed  of  a yellow  and  of  a brown  looking  sub- 
stance; it  has  not,  however,  occurred  to  me  to  see  the' dis- 
tinction in  a very  satisfactory  way. 

The  Vena  Portarum  having  arisen  from  the  junction  of 
all  the  veins  of  the  stomach,  intestines,  pancreas,  and 
spleen,  is  about  three  inches  in  length  when  it  reaches  the 
transverse  fissure,  by  going  over  the  duodenum  and  under 
the  pancreas.  It  immediately  divides  into  two  branches, 
called  collectively  the  Sinus  Venae  Portarum,  which  is  at 
right  angles  with  the  trunk  of  the  vein;  the  right  branch 
being  the  shortest  and  largest,  is  distributed  by  radiating 
trunks  to  the  right  lobe  of  the  liver;  the  left  branch  is  dis- 
tributed, after  the  same  manner,  to  the  left  lobe,  to  the  lo- 
bulus  spigelii,  and  to  the  lobulus  quartus.  Some  of  its 


52 


ORGANS  OF  DIGESTION. 


branches  anastomose  with  the  hepatic  veins,  which  accounts 
for  tlie  ease  with  which  an  injection  will  pass  from  one 
to  the  otlier.  Other  branches  of  a smaller  description  anas- 
tomose with  the  pori  biliarii,  but  with  less  freedom  than  in 
the  preceding  case;  and  lastly  the  most  delicate  ramifica- 
tions are  spent  upon  the  cortical  or  yellow  matter  of  the 
acini,  without  penetrating  to  the  brown.  * 

The  Hepatic  Artery  is  a branch  of  the  cceliac,  and  in  ap- 
proaching the  transverse  fissure  divides  into  three  or  more 
branches,  that  penetrate  the  substance  of  the  liver,  between 
the  sinus  portarum  and  the  ducts  as  they  come  out;  one 
branch  goes  to  the  right  lobe,  another  to  the  left,  and  a third 
to  the  lobulus  spigelii.  There  is  some  variety  in  regard  to 
the  precise  mode  of  distribution,  and  their  division  into 
subordinate  ramifications  frequently  occurs  before  they  get 
fairly  into  the  substance  of  the  liver.  When  there,  they 
seem  to  be  intended  for  the  nourishment  of  this  organ,  ac- 
cording to  the  observations  of  several  able  anatomists;  and 
follow  the  ramifications  of  the  vena  portarum  and  of  the 
biliary  ducts,  forming  upon  them  a very  delicate  and  com- 
plicated tissue  of  anastomosing  vessels,  some  of  which,  pro- 
bably the  vasa  vasorum,  communicate  with  the  vena  por- 
tarum. 

The  Pori  Biliarii,  or  the  commencing  ramifications  of  the 
biliary  duct,  take  their  origin  in  the  acini;  and,  as  is  said, 
upon  the  boundary  between  the  two  kinds  of  matter,  avoid- 
ing the  brown  and  passing  through  the  cortical,  t The 
larger  branches  converge  into  their  respective  trunks  suc- 
cessively or  in  pairs;  while  the  primordial,  or  most  minute 
ones,  converge  several  of  them  to  the  same  point,  giving  a 
penicillous  appearance.  It  is  asserted  that  a fine  injection 
passes  more  readily  from  them  into  the  lymphatics  than  into 
any  other  order  of  vessels,  which  may  account  for  the 
promptitude  of  jaundice  upon  an  obstruction  of  the  hepatic 
duct.  . 


Mappes,  I.  F.  Meckel,  loc.  cit. 


f I.  F.  Meckel,  loc.  cit. 


THE  LIVER. 


53 


The  Hepatic  Veins  arise  in  the  acini  from  the  capillary 
terminations  of  the  vena  portarum  and  the  hepatic  artery. 
Their  branches  are  successively  accumulated  into  three  large 
trunks,  the  collective  area  of  which  vastly  exceeds  that  of 
the  vessels  bringing  the  blood  to  the  liver.  Two  of  these 
trunks  come  from  the  right  lobe  and  one  from  the  left,  to 
empty  into  the  ascending  cava,  while  it  is  still  in  contact 
with  the  liver,  immediately  below  the  diaphragm;  just  be- 
low the  preceding  trunks  there  are  five  or  six,  sometimes 
more  small  hepatic  veins,  coming  from  the  posterior  margin 
of  the  liver,  and  from  the  lobulus  spigelii.  The  hepatic 
veins  are  destitute  of  valves,  and  remarkable  for  the  thin- 
ness of  their  parietes.  An  injection  passes  readily  from 
them  into  the  other  systems  of  vessels.  They  may  be  re- 
cognised by  their  insulated  course,  by  their  consisting  in 
trunks  which  converge  from  the  periphery  of  the  liver  to 
the  vena  cava,  while  all  the  other  vessels  diverge  from  the 
transverse  fissure  to  the  periphery,  and  consequently  cross 
the  course  of  the  hepatic  veins. 

At  the  bottom  of  the  transverse  fissure  of  the  liver  is  to 
be  found  a condensed  cellular  fibrous  tissue,  which  invests 
the  vena  portarum,  the  hepatic  artery,  and  the  biliary 
ducts;  and,  as  they  all  keep  together  in  their  ramifications, 
this  tissue  follows  them  throughout  the  substance  of  the 
liver,  and  thereby  forms  sheaths  for  them.  It  may  be  con- 
sidered as  continuous  with  the  processes  sent  in  from  the 
cellular  coat;  and  contrary  to  the  opinion  of  Glisson,  whose 
capsule  it  has  been  called,  it  is  devoid  of  muscular  structure. 


Of  the  Gall-Bladder. 

The  Gall-Bladder  {Cistis  Fellea)  is  a reservoir  for  the 
bile  secreted  by  the  liver.  It  is  fixed  on  the  under  surface 
of  the  great  lobe,  to  the  right  of  the  umbilical  fissure,  and 
removed  from  the  latter  by  the  lobulus  quartus.  It  is  an 
oblong  pyriform  sac,  having  its  anterior  extremity  or  fun- 
VoL.  II.— S 


54 


ORGANS  OF  DIGESTION. 


dus  projecting  somewhat  beyond  the  anterior  margin  of  the 
liver,  while  the  posterior  end  reaches  to  the  transverse  fis- 
sure. Its  long  diameter  inclines  slightly  to  the  right  side, 
so  that  it  is  not  precisely  in  an  antero-posterior  line.  It 
varies  in  its  shape  in  different  subjects,  being  much  more 
spheroidal  in  some  than  in  others.  Its  fundus  is  round- 
ed and  obtuse,  while  the  posterior  end  is  gradually  reduced 
to  a narrow  neck,  which  is  bent  up  on  itself,  so  as  to  retard 
the  flow  of  a fluid  through  it.  Its  upper  surface  is  in  con- 
tact with  the  substance  of  the  liver,  and  is  received  into  a 
broad  shallow  fossa,  while  the  lower  surface  is  projecting, 
and  by  coming  in  contact  with  the  transverse  colon,  tinges 
it  with  bile,  by  transudation  after  death. 

The  Gall-Bladder  has  three  coats,  a peritoneal,  a cellular, 
and  a mucous  one. 

The  Peritoneal  Coat  is  not  complete,  but  only  covers  that 
part  of  the  sac  not  received  into  the  fossa  on  the  under  sur- 
face of  the  liver;  it  is,  therefore,  a continuation  of  the  pe- 
ritoneal coat  of  the  latter;  sometimes,  however,  the  gall- 
bladder is  so  loosely  attached  to  the  liver  that  it  almost 
hangs  off  from  it,  in  which  case  the  peritoneal  coat  is  nearly 
complete. 

The  second  coat  is  condensed  cellular  membrane.  Through 
it  ramifies  a great  number  of  lymphatics,  and  blood  vessels; 
below,  it  attaches  the  peritoneal  to  the  mucous  coat,  and 
above,  the  latter  to  the  liver. 

The  Mucous  Coat  is  always  tinged  of  a deep  green  or 
yellow,  by  the  bile  which  it  contains  percolating  after  death; 
for  it  is  said  to  be,  before  that,  of  a light  colour.  This 
coat  is  thrown  into  irregular  tortuous  folds  or  wrinkles  of 
extreme  delicacy,  in  the  intervals  of  which  are  many  round 
or  polyedrous  cells,  causing  it  to  look,  when  floated  in  wa- 
ter, like  a fine  honeycomb;  such  as  are  about  the  fundus  of 
the  sac  are  superficial,  and  not  so  distinct;  but  those  near 
its  middle  and  about  the  neck,  are  a line  or  a line  and  a half 
deep.  In  the  neck  or  apex,  and  in  the  beginning  of  the 
cystic  duct,  are  from  three  to  seven,  sometimes  twelve,  se- 
milunar duplicatures  of  the  internal  membrane,  which  also 


THE  LIVEK. 


55 


retard  the  flux  and  afflux  of  any  fluid,  though  they  do  not 
afibrd  so  much  resistance  to  the  ingress  as  to  the  egress  of 
it.  These  duplicatures  are  sometimes  arranged  into  a spiral 
valve,  projecting  from  the  inside  of  the  duct,  and  forming 
two  or  three  turns.*  Very  small  mucous  follicles  exist 
over  the  internal  face  of  this  membrane,  the  discharge  of 
which  fills  the  gall-bladder  when  the  secretion  of  bile  has 
been  interrupted  by  diseased  action,  as  in  yellow  fever,  or 
by  scirrhus  of  the  liver. 

The  artery  of  the  gall-bladder  is  a branch  of  the  hepatic. 
Its  veins  empty  into  the  vena  portarum.  Its  nerves  come 
from  the  sympathetic,  and  its  lymphatics  join  those  of  the 
liver. 

Of  the.  Biliary  Ducts. 

A succession  of  very  fine  branches  having  arisen  from  the 
acini  of  the  liver,  these  branches  are  united  into  three  or 
four  trunks  by  the  time  they  reach  the  transverse  fissure. 
These  trunks  then  coalesce  into  a single  one,  the  Hepatic,  of 
eighteen  or  twenty  lines  in  length,  and  about  the  diameter  of 
a writing  quill.  The  Hepatic  Duct  is  then  joined  at  a very 
acute  angle  with  the  duct  from  the  gall-bladder,  which  is 
somewhat  shorter  and  smaller;  the  union  of  the  two  forms 
the  Ductus  Communis  Choledochus.  The  latter  is  larger  than 
either  of  the  others  singly,  and  is  three  or  three  and  a half 
inches  long;  it  descends  behind  the  right  extremity  of  the 
pancreas  through  its  substance,  passes  for  an  inch  obliquely 
between  the  coats  of  the  duodenum,  becoming  at  the  same 
time  diminished  in  diameter;  and  finally  ends  by  an  orifice 
still  more  contracted,  on  the  internal  face  of  this  gut,  in  its 
second  turn,  and  about  three  or  four  inches  from  the  stomach. 
The  orifice  is  marked  by  a small  surrounding  tubercle  some- 
what obscured  by  the  valvulae  conniventes. 

The  Biliary  Ducts  are  situated  along  the  right  margin  of 

* Discovered  latterly  by  M.  Amussat  of  Paris.  M.  Amussat  has  also  de- 
tected muscular  fibres  in  the  gall-bladder  and  biliary  ducts,  in  which  \vc 
see  an  analogy  with  other  hollow  viscera. — Am.  Med.  Jour,  vol,  ii.  p.  195. 


ORGANS  OF  DIGESTION. 


OtJ 

llie  lesser  omentum,  and  have  the  vena  portarum  and  the 
hepatic  artery  to  their  left.  The  reflection  of  the  pei’itoneuni 
along  witli  the  cellular  substance  which  includes  these  several 
parts,  is  spoken  of  frequently  under  the  term  Capsule  of 
Glisson. 

The  bile  ducts  are  formed  by  two  coats;  the  external  is  a 
librous,  lamellated,  and  very  extensible  membrane,  while  the 
internal  is  mucous,  having  the  same  structure  with  that  of 
the  gall-bladder,  of  which  it  is  in  direct  continuation.  In 
the  Cystic  Duct,  and  at  the  lower  part  of  the  Common  Duct, 
are  several  longitudinal  folds.  The  Common  Duct  some- 
times receives,  just  before  it  empties  into  the  duodenum,  the 
pancreatic  duct. 

Of  the  Bile. 

This  secretion  from  the  liver,  is  of  a deep  yellow,  some- 
times green  colour;  when  recently  secreted,  it  is  thin  and 
fluid;  but  after  it  has  been  conveyed  to  the  gall-bladder,  and 
permitted  to  remain  there  for  some  time,  it  becomes  as  thick 
as  molasses,  and  increases  also  in  the  intensity  of  its  colour 
and  in  bitterness.  Some  anatomists  have  believed  that  there 
was  a more  direct  communication  between  the  liver  and  the 
gall-bladder  than  that  through  the  hepatic  and  the  cystic 
duct;  but  repeated  and  close  observations  have  proved  the 
opinion  to  be  erroneous,  or,  at  least,  destitute  of  proper 
proof;  it  is,  thei'efore  clear,  that  the  diflerence  between 
the  hepatic  and  the  cystic  bile,  depends  upon  the  watery  par- 
ticles being  removed  from  the  latter,  by  the  absorbing  pow- 
er of  the  internal  coat  of  the  gall-bladder. 

According  to  Berzelius  the  chemical  analysis  of  bile  fur- 
nishes about  eighty  parts  of  water,  eight  of  a particular  sub- 
stance which  assumes  a resinous  condition  on  the  application 
of  an  acid;  three  of  mucus;  and  nine  of  saline  matters,  of 
which  soda  is  a principal  constituent. 


THE  SPLEEN. 


57 


SECT.  II. — OP  THE  SPLEEN. 

The  Spleen  (Lie7i,  Splen)  is  situated  deeply  in  the  poste- 
rior part  of  the  left  hypochondriac  region,  and  is  bounded 
above  by  the  diaphragm,  below  by  the  colon,  and  on  the 
right  by  the  great  end  of  the  stomach,  and  by  the  pan- 
creas. 

Its  colour  varies  from  a deep  blue  to  a dark  brown.  In 
shape  it  resembles  the  longitudinal  section  of  an  oval,  being 
flat  or  very  slightly  concave  on  the  surface  next  to  the  sto- 
mach and  convex  on  that  contiguous  to  the  diaphragm. 
Occasionally  its  margins  are  notched,  but  this  is  not  invari- 
ably the  case.  Its  flat  surface  is  slightly  depressed  longitu- 
dinally in  the  centre,  where  the  blood  vessels  enter  it  by  six 
or  eight  foramina. 

Several  spleens  sometimes  exist  in  the  same  individual, 
in  which  case  the  supernumerary  ones  are  not  larger  than 
nutmegs.  The  common  size  of  this  organ  is  about  four  and  a 
half  inches  long,  by  two  and  a half  or  three  wide,  in  which 
case  it  has  a solid  firm  feel;  but  it  very  often  exceeds  these 
dimensions;  its  transition  and  varieties  of  magnitude  are  so 
frequent,  that  no  settled  rule  can  be  established.  In  its  in- 
ordinate enlargements  I have  seen  it  only  slightly  smaller 
than  the  liver,  its  texture  in  this  case  is  soft  and  easily  la- 
cerated. 

It  is  fixed  in  its  place  by  three  points  of  reflection  or 
processes  of  peritoneum,  whose  names  indicate  sufficiently 
their  places  of  attachment.  They  are  the  Gastro-Splenic 
Ligament,  in  which  are  the  vasa  brevia  of  the  stomach;  the 
Splenico-Phrenic;  and  the  Splenico-Colic.  These  reflec- 
tions by  being  continued  over  the  spleen,  give  it  a complete 
peritoneal  coat,  which  is  raised  up  with  more  difficulty, 
than  the  corresponding  membrane  of  any  other  viscus  of 
the  abdomen. 

The  Internal  or  proper  coat  of  the  spleen  is  a grayish, 
compact,  extensible,  and  elastic  membrane,  the  use  of  which 


58 


ORGANS  OP  DIGESTION- 


is  evidently  to  sustain  the  natural  shape  of  the  organ,  and 
to  support  its  parenchymatous  structure.  It  sends  in  pro- 
cesses to  accompany  the  blood  vessels,  and  from  its  internal 
face  there  proceeds  a multitude  of  lamellai  and  of  fibres, 
w^hich  traverse  its  cavity  in  every  direction,  and  reduce  it 
into  a cellular  condition  not  unlike  the  spongy  structure  of 
bones. 

The  spleen,  in  proportion  to  its  size,  is  furnished  to  a re- 
markable degree  with  blood.  The  largest  branch  of  the 
cceliac  artery  runs  to  it  along  the  superior  margin  of  the 
pancreas,  forming  numerous  serpentine  flexures,  and  dis- 
tinguished for  its  thickness;  it  divides  into  several  trunks 
for  penetrating  into  the  spleen,  and  enters  by  the  foramina 
in  the  fissure.  The  veins  come  out  by  a number  of  trunks 
equal  to  what  the  artery  is  divided  into;  they  assemble  then 
into  a single  trunk,  which  attends  the  artery  along  the  pan- 
creas, and  is  remarkable  for  the  tenuity  and  extensibility 
of  its  coats.  The  splenic  vein  is  destitute  of  valves,  and 
empties  into  the  vena  portarum.  The  spleen  has  also  lym- 
phatic vessels;  and  is  furnished  with  nerves  from  the  solar 
plexus. 

Of  the  Intimate  Structure  of  the  Spleen. — The  Sple- 
nic artery  having  penetrated  into  this  organ,  is  divided  and 
subdivided  into  a radiating  succession  of  very  fine  branches, 
which  according  to  the  injections  of  Ruysch  do  not  anasto- 
mose with  each  other;  in  consequence  of  which,  one  part 
is  sometimes  finely  injected  and  not  another,  of  which,  in 
my  own  observations,  I have  had  an  example.  The  veins, 
on  the  contrary,  do  anastomose,  not  only  as  regards  the 
collateral  branches  of  the  same  primitive  trunk,  but  also  by 
the  collateral  branches  of  different  trunks.  These  anasto- 
moses are  not  large.  The  arteries  terminate  freely  in  the 
veins,  as  may  be  proved  by  fine  injections,  and  by  the  mi- 
croscope. 

The  mass  of  the  spleen,  upon  superficial  examination, 
seems  to  consist  in  a dark  brown  pulp,  contained  in  the 
cells  dividing  the  cavity  of  the  internal  coat,  and  may  be 


THE  spleen- 


59 


easily  demonstrated  by  tearing  the  spleen,  and  scraping  it 
with  a knife  handle.  MM.  Assolont  and  Meckel  believe, 
that  blood,  besides  being  in  the  arteries  and  veins,  is  placed 
in  a state  of  particular  combination  and  of  intimate  union 
with  the  other  organic  elements  of  this  viscus,  and  with  a 
large  quantity  of  albumen;  and  that  this  combination  of  the 
blood  forms  the  dark  brown  pulp  alluded  to.  The  great 
quantity  of  albumen  in  the  pulp,  is  readily  proved  by  the 
hard  coagulum  which  it  forms,  when  steeped  in  alcohol. 
But  a question  has  arisen  whether  the  pulp  is  extravasated 
in  the  cells  which  contain  it,  or  whether  it  is  still  retained 
in  the  extremities  of  the  blood  vessels.  Superficial  exami- 
nation is  in  favour  of  the  first,  but  M.  Marjolin  denies  it  on 
the  following  grounds;  that  injections  cautiously  made  pass 
immediately  from  the  arteries  to  the  veins;  and  that  the 
spleen,  when  successfully  injected  and  frozen,  does  not  ex- 
hibit ice  in  the  interstices  of  its  vessels,  while  their  capil- 
lary ramifications,  distended  by  the  injected  fluid,  are  dis- 
tinctly seen.  From  these  he  concludes  that  the  glandular 
structure  of  the  spleen  is  formed  essentially  of  arterial  and 
venous  capillary  vessels  with  very  delicate  and  extensible 
coats,  and  that  they  communicate  with  one  another  without 
the  intermedium  of  any  cell;  that  the  extreme  tenuity  of 
these  vessels,  and  their  extensibility  in  every  direction,  are 
sufficient  to  explain  the  augmentation  of  volume  of  the 
spleen,  under  certain  circumstances,  as  well  as  the  promp- 
titude of  its  diminution  under  others. 

In  addition  to  this  pulp,  many  observers  have  met  in  the 
spleen  with  an  abundance  of  rounded  corpuscles,  varying 
in  size  from  an  almost  imperceptible  magnitude  to  a line  or 
more  in  diameter.*  They  are  of  a gelatinous  consistence, 
soft,  grayish,  and  semi-transparent,  and  either  cluster  toge- 
ther, or  are  widely  separated.  By  Malpighi  they  were 
considered  glandular,  and  by  Ruyscht  as  convoluted  ves- 

* Malpighi,  Ruysch,  Hewson,  Home,  Dupuytren,  Meckel,  &c. 

■J-  Epist.  Anat.  IV. 


CO 


ORGANS  OF  DIGESTION. 


sels.  Professor  Soemmering,  from  the  following  paragraph, 
seems  to  join  in  the  opinion  of  the  latter:  “Qni  nonnun- 
quam  ocourrunt,  acini  vel  glomeruli,  microscopii  ope  ac- 
curatissime  exploi’ati  nihil  sunt,  nisi  vasorum  fasciculi,  vel 
teretes  penicilli  aut  cirri  vasculosi.”  According  to  the  ob- 
servations of  Sir  Evd.  Home,  they  swell  considerably  after 
an  animal  has  finished  drinking. 

The  spleen,  from  having  no  excretory  duct,  and  conse- 
quently from  our  inability  to  ascertain  whether  it  secretes, 
has  its  nature  and  uses  shrouded  in  mystery.  No  single 
theory  concerning  it  has  ever  been  generally  adopted,  for 
speculations  have  multiplied  in  proportion  to  the  obscurity 
of  the  subject.  The  idea  however  on  the  use  of  this  body, 
which  to  me  is  most  reasonable,  is,  that  it  acts  a subsidiary 
part  to  the  liver.  It  would  seem,  indeed,  as  a general  rule 
in  regard  to  glandular  structures  and  such  other  highly  vas- 
cular organs  of  the  body  as  have  an  intermittent  function, 
that  the  blood  which  is  sent  to  them  during  their  state  of 
activity,  should  be  passed  oflf  during  a different  channel, 
while  they  are  in  a state  of  repose.  This  does  a double 
service,  it  prevents  superfluous  secretions,  and  it  also  keeps 
up  the  vascular  equilibrium  of  the  body,  as  there  must  be 
always  in  readiness  a quantity  of  blood  sufficient  for  the 
supply  of  any  secretion  which  may  be  wanted  for  the 
time. 

This  proposition  will  derive  some  additional  illustrations 
from  the  foetal  state.  The  kidneys  being  then  inactive  the 
glandulae  renales  take  off  their  blood,  and  thereby  prevent 
what  would  otherwise  be  a very  inconvenient  secretion  of 
urine;  again,  the  lungs  being  also  then  inactive,  the  circu- 
lation through  them  is  proportionately  reduced,  and  the  su- 
perabundant blood  is  circulated  through  the  thymus  gland. 
But  as  the  full  functions  of  the  lungs  and  of  the  kidneys  are 
established  upon  birth,  and  continue  uninterrupted  during 
life,  their  supplementary  organs,  the  thymus  gland,  and 
the  capsulae  renales,  are  not  wanted,  and  they  wither  away 
after  the  early  period  of  infantile  existence  is  passed. 

But  in  regard  to  the  liver,  its  functions  also  suspended 
during  fetal  life,  are  of  an  intermittent  kind  throughout 


THE  PANCREAS. 


65 


iife,  the  spleen  may  therefore  be  considered  a vicarious  or- 
gan for  it  during  the  whole  period  of  existence,  receiving 
its  blood  during  the  continuation  of  uterine  life,  and,  in  the 
intermission  of  action,  during  common  life.  The  spleen  is 
therefore  an.organ  useful  to  tire  foetal  and  to  the  perfect  state, 
and  we  consequently  never  see  it  in  the  collapsed  and  dwin- 
dled condition  of  the  thymus  and  renal  gland. 

The  same  reasoning  which  applies  to  the  spleen  will  also 
apply  to  the  Thyroid  Gland,  for  the  latter  may  be  consi- 
dered as  executing  for  the  salivary  glands,  during  foetal  and 
perfect  existence,  what  the  spleen  does  for  the  liver.  For 
it  is  ascertained,  that  the  salivary  glands  are  inactive  during 
foetal  existence,  have  only  an  intermittent  action  during 
perfect  life,  and  therefore  probably  stand  in  need  of  a sup- 
plementary organ  during  their  periods  of  inactivity. 

SECT.  III. OF  THE  PANCREAS. 

The  Pancreas  {Pancreas)  is  the  largest  of  the  salivary 
glands.  It  is  fixed  in  the  lower  back  part  of  the  epigastric 
region,  and  extends  horizontally  across  the  spine,  being 
separated  from  it  by  the  lesser  muscle  of  the  diaphragm.  It 
is  connected  to  the  spleen  on  the  left;  at  its  right  extremi- 
ty is  surrounded  by  the  curvature  of  the  duodenum;  is 
bounded  in  front  by  the  stomach,  which  conceals  it;  and 
is  placed  between  two  laminae  of  the  mesocolon. 

The  pancreas  is  about  six  or  seven  inches  long,  two  wide, 
and  flattened  before  and  'behind.  Its  figure  would  be  re- 
presented by  a parallellogram,  were  it  not  that  its  right 
extremity  is  enlarged  considerably  into  a head  or  tuber, 
to  which  Winslow  gave  the  name  of  the  Lesser  Pancreas. 
The  anterior  face  of  this  organ  is  turned  obliquely  upwards, 
and  is  covered  by  the  superior  lamina  of  the  mesocolon. 
The  posterior  face  looks  obliquely  downwards,  and  is  in 
contact  with  the  aorta,  the  vena  cava  ascendens,  the  su- 
perior mesenteric  vessels,  and  several  nerves;  along  the  su- 
perior margin  of  this  face  exists  a long  superficial  fossa,  oc- 
cupied by  the  splenic  artery  and  vein. 

VoL.  II. —9 


66 


ORGANS  OF  DIGESTION. 


With  the  exception  of  the  loose  covering  given  by  the 
mesocolon,  the  pancreas  has  no  peritoneal  coat;  neither 
has  it  an  appropriate  tunic,  unless  we  consider  as  such  the 
lamina  of  condensed  cellular  membrane  which  envelops  it, 
and  sends  in  processes  between  its  lobules,  as  in  the  case  of 
the  salivary  glands  in  the  neck. 

Of  the  Minute  Structure  of  the  Pancreas. — This  body, 
like  the  other  glands  which  discharge  saliva,  is  of  a light  gray 
or  pink  colour.  It  consists  in  lobules  of  various  forms  and 
sizes,  united  by  an  intermediate  cellular  tissue,  and  having 
their  interstices  occupied  by  numerous  blood  vessels.  These 
lobules,  by  a slight  maceration,  may  be  separated  and  re- 
solved into  small  granular  masses,  constituting  integral  por- 
tions of  the  gland. 

The  arteries  of  the  pancreas  come  principally  from  the 
splenic,  as  it  cruises  along  the  superior  margin.  The  veins 
empty  into  the  splenic,  and  thus  finally  into  the  vena  por- 
tarum.  It  is  furnished  with  nerves  from  the  solar  plexus, 
and  has  lymphatics. 

The  excretoiy  duct  of  this  gland  {JDuctus  Wirsungii) 
arises,  by  very  fine  roots  or  tubes,  from  each  of  the  small 
granular  masses.  These  tubes  coalesce  into  larger  ones, 
which  run  transversely  from  the  periphery  towards  the 
centre  of  the  gland,  inclining  slightly,  at  the  same  time,  to- 
wards the  right.  These  secondary  tubes  finally  discharge 
successively  into  a single  one,  which  runs  the  whole  length 
of  the  gland  nearly  in  its  middle.  The  single  tube,  by 
these  additions,  enlarges  continually  from  left  to  right, 
being  small  where  it  begins  at  the  splenic  extremity  of  the 
pancreas,  and  about  the  size  of  a crow  quill  at  the  duodenal. 
At  the  latter  place  it  is  joined  by  the  duct  of  the  lesser 
pancreas,  which  is  derived  after  the  same  rule  as  itself.  The 
pancreatic  duct,  almost  immediately  afterwards,  empties 
into  the  ductus  communis  choledochus,  or  runs  at  the  side 
of  the  latter,  and  makes  a distinct  opening  near  it  into  the 
duodenum,  at  the  posterior  part  of  the  second  curvature. 


BOOK  V. 


OF  THE  URINARY  ORGANS. 

The  Urinary  Organs,  (^Organa  Uropoietica,)  being 
destined  to  secrete  and  to  convey  the  urine  out  of  the  body, 
consist  in  the  Kidneys,  the  Renal  Capsules,  the  Ureters, 
the  Bladder,  and  the  Urethra. 

Of  the.  Kidneys. 

The  Kidneys  (Kenes)  are  two  glandular  bodies,  lixed  one 
on  either  side  of  the  spine,  for  the  secretion  of  urine.  They 
are  in  the  back  part  of  the  lumbar  regions,  have  their  spinal 
edges  inclining  very  slightly  forwards,  and  extend  from  the 
upper  margin  of  the  eleventh  dorsal  to  the  lower  margin  of 
the  second  lumbar  vertebra;  the  right,  however,  is  ten  or 
twelve  lines  lower  down  than  the  left,  owing  to  the  thick  pos- 
terior margin  of  the  right  lobe  of  the  liver,  which  presses  it 
downwards.  The  kidneys  are  covered  in  front  by  the  peri- 
toneum and  lumbar  portions  of  the  large  intestine,  but  in 
such  a manner  as  to  be  separated  from  them  by  a thick  sur- 
rounding layer  of  fat;  behind,  they  repose  upon  the  lower 
part  of  the  great  diaphragm,  upon  the  quadrati  lumborum, 
and  upon  the  upper  end  of  the  psoae  magni  muscles. 

The  kidney  is  a hard  solid  body,  of  a brown  colour;  in 
shape  it  is  a compressed  ovoid,  excavated  on  the  margin 
which  it  presents  to  the  spine,  and  bears  a very  strong  re- 
semblance to  the  common  kidney  hean.  Its  flat  surfaces  pre- 
sent forwards  and  backwards,  and  the  broad  end  of  the  ovoid 
is  above.  Its  periphery  is  smooth,  so  that  one  does  not  see 
from  an  external  examination  the  lobules  or  internal  divi- 
sions. The  excavation  of  the  kidney,  called  its  fissure 


rillNARV  OKGAXS. 


()S 

(hilum  renalc)  occupies  about  one-third  of  its  long  diameter, 
is  bevelled  in  front,  and  leads  to  the  very  intei’ior  of  the 
gland;  conducting  its  blood  vessels  and  excretory  duct, 
which  have  to  pass  through  a quantity  of  cellular  and  adi- 
pose matter.  The  kidneys  are  generally  of  equal  size,  being 
about  four  inches  long,  and  two  wide;  and  each  one  weighs 
three  or  four  ounces.  They  have  no  ligaments  for  keeping 
them  in  position,  but  depend  for  the  latter  upon  the  adja- 
cent cellular  adhesions  and  blood  vessels. 

The  kidney  being  destitute  of  a peritoneal  coat,  has  a well 
marked  capsule  which  envelops  it  entirely  and  jienetrates 
into  its  fissure  for  some  depth,  where  it  is  perforated  with 
foramina  for  transmitting  the  blood  vessels  and  the  ureter. 
This  capsule  is  white,  semi-transparent,  fibrous,  strong,  and 
elastic:  it  adheres  to  the  surface  of  the  kidney  by  delicate 
cellular  and  vascular  filaments,  which  are  so  weak  that  they 
permit  it  to  be  stripped  off  without  difficulty,  and  when  so 
removed,  some  remains  of  the  original  lobulated  condition 
of  the  organ  are  manifested. 

The  kidney  receives  from  the  aorta  one  or  more  branches, 
called  the  renal  or  emulgent  arteries;  they  divide  as  they 
approach  the  fissure,  and  having  got  into  the  substance  of 
the  gland  are  distributed  by  innumerable  twigs  to  all  parts 
of  it.  Some  terminate  in  veins,  others  in  the  substance 
of  the  organ,  and  others,  again,  in  the  excretory  tubes. 
The  veins  equal  in  number  the  arteries,  and  are  somewhat 
larger.  When  both,  or  even  one,  of  these  systems  of  blood 
vessels  is  injected  with  wax  and  corroded,  its  branches  are 
so  abundant  as  to  maint&in  the  form  of  the  gland.  In  en- 
gaging in  the  fissure  of  the  kidney,  the  arterial  ramifications 
are  in  front,  the  veins  in  the  middle,  and  the  commence- 
ment of  the  ureter  behind.*  The  artery  on  the  right  side 
is  longer  than  that  on  the  left.  The  reverse  is  the  case 
with  the  emulgent  veins,  as  they  empty  into  the  vena  cava' 
ascendens.  This  arrangement  is  owing  to  the  relative  po- 
sition of  the  aorta  and  the  vena  cava  ascendens,  as  the  fir&t 
is  on  the  left  side  of  the  spine  and  the  last  on  the  I’ight 
side. 

* This  rule  is  subject  to  frequent  variations. 


THE  KIDNEES. 


69 


The  nerves  come  from  the  solar  plexus  of  the  sympa- 
thetic, and  adhering  to  the  arteries  cannot  be  traced  very 
far  through  the  glandular  structure.  The  quantity  of  lym- 
phatics is  considerable. 

Of  the  Minute  Structure  of  the  Kidney. — When  the 
kidney  is  cut  open  longitudinally,  it  obviously  consists  of 
two  kinds  of  substance,  differing  in  their  situations,  colour, 
consistence  and  texture.  The  one  nearest  to  the  periphery 
of  the  gland  is  called  from  its  position  Cortical  {Substantia 
Corticalis,  Glandulosa)  while  the  other,  being  more  in- 
ternal, is  designated  as  the  Medullary  or  Tubular  {Sub- 
stantia Medullaris;  Tubulosa;  Fibrosa.) 

The  Cortical  or  Secretory  Substance  forms  the  whole 
circumference  of  the  kidney,  and,  on  an  average,  is  about 
two  lines  in  thickness 5 but  it  is  thicker  at  some  points,  as 
from  its  interior  face  processes  converge  towards  the  centre 
of  the  gland,  which  separate  the  tubular  part  into  as  many 
distinct  portions  of  a conoidal  shape.  It  is  composed  prin- 
cipally of  arteries  and  veins  ramifying  among  small  grani- 
form  coi’puscles,  that  secrete  the  urine,  and  are  very  dis- 
tinct when  viewed  with  a microscope.  It  tears  with  facili- 
ty, thereby  presenting  this  granular  appearance,  and  is  of  a 
dark,  or  reddish  brown  colour,  varying  considerably,  how- 
ever, according  to  the  cause  of  death. 

The  granular  corpuscles  which  form  the  mass  of  the  cor- 
tical or  Secretory  substance,  are  individually  imperfectly 
visible  to  the  naked  eye,  and  appear  like  rounded  points. 
The  celebrated  Ruysch,  who  was  distinguished  for  the  suc- 
cess of  his  injections,  and  for  the  acuteness  of  his  vision, 
declared  that  they  consisted  wholly  in  the  very  fine  extre- 
mities of  arteries  and  veins  having  a penicillous  arrange- 
ment; while  Malpighi  and  Schumlansky  viewed  them  as 
purses  or  small  sacs  of  a glandular  character  specifically 
suited  to  secrete  urine,  and  upon  whose  parietes  the  blood 
vessels  ramified.  From  these  granuli  the  incipient  extre- 
mities of  the  tubuli  uriniferi  take  their  rise. 


70 


UKINARY  ORGANS. 


The  Tubular  or  Conoidal  portion,  consists  in  from  twelve 
to  eighteen  conoidal  fasciculi  {Pyramides  Malpighianas) 
presenting  their  rounded  bases  towards  the  cortical  matter, 
and  enclosed  in  it,  while  their  apices  converge  to  the  cen- 
tral cavity  of  the  kidney,  the  surface  of  which  they  form. 
The  bodies  of  these  pyramids,  as  just  mentioned,  are  se- 
parated by  processes  of  the  cortical  matter;  but  their  apices 
are  free,  and  project  from  the  internal  surface  of  the  kid- 
ney so  as  to  resemble  as  many  small  nipples,  whence  the3>" 
are  called  Papillae  Renales.  Frequently  two  of  the  pyra- 
mids coalesce  so  as  to  form  but  one  papilla  together;  in  such 
case  the  latter  generally  preserves  a duplicate  appearance. 
The  papillae  are  arranged  into  three  vertical  rows,  one  be- 
fore, one  in  the  middle,  and  another  behind;  those  of  the 
foremost  row  are  turned  backwards;  those  of  the  middle 
look  inwards;  and  those  behind  look  forwards.  Not  un- 
frequently  there  is  a small  depression  [foveola)  on  the 
very  summit  of  the  papilla.  The  tubular  part  is  of  a lighter 
colour  and  harder  than  the  cortical,  but  the  difference  in 
these  respects  is  not  always  very  manifest. 

The  conoidal  fasciculi  may  each  be  considered,  along  with 
its  appertaining  cortex,  as  a sort  of  distinct  gland,  or  at  least 
as  a lobe;  for  upon  them  depend  the  lobulated  appearance 
of  the  kidneys  of  a foetus,  and  of  animals.  Each  cone, 
when  analyzed,  is  found  to  consist  in  a collection  of  tubes 
{Ductus  Uriniferi  Bellini)  converging  from  the  circum- 
ference of  the  kidney  to  the  apex  of  the  papilla.  These 
tubes  are  more  numerous  near  the  base  in  consequence  of 
their  successive  junction  in  approaching  the  apex;*  their 
terminating  orifices,  on  the  latter,  appear  like  small  pores, 
from  which  the  urine  can  be  squeezed  in  little  drops. 

In  the  early  part  of  the  course  of  the  ductus  uriniferi, 
while  they  are  still  in  the  cortical  matter,  they  are  wound 
up  in  a very  serpentine  and  tortuous  manner,  and  are  distin- 
guished by  the  name  of  cortical  canals,  or  ductus  Ferrenii.t 
They  commonly  go  alone,  winding  their  way  in  the  corti- 

* Schumlansky,  Dis.  de  Struct.  Eenum,  Strasburg,  1788. 

f A.  Ferrein;  sur  la  Structure  des  reins  et  du  foie,  Mem.  de  Paris,  1749. 


THE  KIDNETS. 


71 


cal  substance  until  they  reach  its  most  interior  face,  they 
then  become  straight,  form  the  medullary  substance,  and 
have  the  name  of  the  conduits  of  Bellini.  * 

Some  of  the  calculations  on  this  subject  are  not  a little 
curious.  It  was  ascertained  by  Ferrein  that  in  each  of  the 
conoidal  fasciculi  (Pyramides  Malpighianas)  there  were, 
at  least,  seven  hundred  subordinate  cones  or  pyramids;  and 
as  the  number  of  cones  is  generally  about  fifteen,  these  p}^- 
ramids’ would  amount  to  ten  tliousand  five  hundred.  Again, 
each  of  the  subordinate  pyramids  (Pyramides  Ferrenii)  is 
composed  of  many  hundred  uriniferous  tubes,  and,  by  the 
observations  of  Eysenhard,t,t  each  of  these  tubes  consists  of 
twenty  smaller  ones. 

The  arteries  of  the  kidneys  in  ramifying,  minutely 
through  its  structure,  adopt  the  following  arrangement. 
They  first  of  all  pass  through  the  processes  sent  inwards 
from  the  cortical  matter  between  the  large  cones,  and, 
having  got  into  the  cortical  matter,  they  divide  into  very 
fine  twigs,  which  form  arcades  around  the  bases  of  the  py- 
ramids of  Ferrein,  and  pass  between  them.!  These  arcades 
have  but  few  anastomoses  with  each  other,  and  their 
branches  go  almost  exclusively  ta  the  cortical  substance, 
very  few  of  them  being  found  on  the  tubular.  Their 
branches  radiate  from  the  convexities  of  the  arches,  so  as  to 
surround  the  base  of  each  cone,  and  to  penetrate  to  the  sur- 
face of  the  kidney.  Some  of  these  branches  terminate  in 
corresponding  veins,  and  others  on  the  granular  corpuscles. 
The  connexion  between  the  corpuscles  and  the  arteries,  has 
been  compared  to  that  between  grapes  and  the  stems  on 
which  they  grow,  so  as  to  form  a bunch.  A similar  con- 
nexion of  the  corpuscles  with  the  veins  is  not  quite  evi- 
dent, and  even,  if  it  does  exist,  remains  yet  to  be  proved.. 
In  one  instance,  I found  in  a young  female  subject  one  of 
the  kidneys  in  the  pelvis  in  front  of  the  rectum.  A similar 
case  has  been  seen  by  Professor  Hensinger;§  and  I have  met 

* L.  Bellini,  cle  Structura  Renum.  Florence,  1662. 

f De  Struct.  Renum.  Obs.  Micros.  Berlin,  1818.  t Schumlansky. 

§ Am.  Med.  .Tour.  Vol.  iii.  p.  442. 


72 


URINARY  ORGANS. 


with  two  instances  of  a coalition  across  the  spine,  of  the  two 
kidneys,  so  as  to  present  the  appearance  of  a bilobed  organ. 

Of  the  Excretory  Duct  of  the  Kidney  or  the  Ureter. 

The  Ureter  is  a canal  which  conveys  the  urine  from  the 
kidney  to  the  bladder.  It  commences  in  the  centre  of  the 
kidney  by  an  enlargement  called  pelvis,  which  branches  off 
into  three  or  four  portions,  (calices)  one  above,  one  below, 
and  one  or  two  intermediate.  Each  of  these  calices  is  di- 
vided, at  its  free  extremity,  into  three  or  four  short  funnel- 
shaped  terminations  (Infundibula.)  Each  of  these  termina- 
tions embraces  by  its  expanded  orifice,  the  base  of  a pa- 
pilla, so  as  to  permit  the  latter  to  project  into  it,  and  thereby 
to  distil  its  urine  there.  Very  frequently  the  number  of  pa- 
pillae exceeds  that  of  the  infundibula,  in  which  case  two  of 
the  former  project  into  one  of  the  latter. 

The  pelvis  of  the  kidney  having  emerged  at  the  fissure  be- 
hind the  vessels,  from  being  expanded  and  somewhat  conoidal 
in  shape  is  reduced  to  a cylindrical  canal,  which,  properly 
speaking,  is  the  ureter:  the  latter  is  about  the  size  of  a goose- 
quill,  and  descends  through  the  lumbar  region,  between  the 
peritoneum,  and  the  psoas  magnus  muscle.  It  dips  into  the 
pelvis  by  crossing  in  front  of  the  primitive  iliac  vessels  and 
the  internal  iliac,  crosses  the  vas  deferens  at  the  back  of  the 
bladder,  and  penetrating  obliquely  the  coats  of  the  latter, 
terminates  in  an  orifice  ten  or  twelve  lines  behind  that  of  the 
neck  of  the  bladder. 

The  excretory  duct  of  the  kidney  is  formed  by  two  coats. 
The  external  is  a condensed,  fibrous,  and  cellular  tissue,  but 
is  destitute  of  any  thing  like  muscle.  The  internal  is  a thin 
mucous  lamina,  which  can  be  raised  up  without  much  diffi- 
culty, and  is  continuous,  at  its  lower  end,  with  the  internal 
coat  of  the  bladder;  at  the  upper  end,  it  is  supposed  by 
some  anatomists  to  be  reflected  over  the  papillae,  and  even  to 
pass  for  some  distance  into  the  tubuli  uriniferi.  This  duct 
has  considerable  powers  of  extension,  as  manifested  by  its 
transmitting  large  calculi  from  the  kidney,  and  also  by  its 


THE  RENAL  CAPSITLES. 


73 


general  enlargement  in  some  cases  of  obstructed  urethra;  its 
sensibility  is  exquisite  when  irritated  by  a calculus  passing 
down  it. 

Of  the  Renal  Capsules. 

The  Renal  Capsules  {Capsulse  Renales,  Renes  Succentu. 
Tiati,)  are  two  small  bodies,  one  on  either  side,,  placed  upon 
the  upper  end  of  the  kidney.  They  are  of  a yellowish 
brown  colour  tinged  with  red,  have  no  excretory  ducts,  and 
are  more  distinctly  developed  and  softer  in  the  perfect  foetus 
than  in  the  adult;  whence  they  are  ranked  among  those  or- 
gans, as  the  thymus  gland,  and  so  on,  which,  having  some 
peculiar  value  in  foetal  existence,  are  perhaps  unnecessary 
to  that  of  the  adult.*  They  are  of  a triangular  pyramidal 
shape,  flattened  before  and  behind,  and  rest  by  a concave 
base  upon  the  kidney;  they  are  about  fifteen  lines  high  and 
as  many  wide. 

They  are  surrounded  by  a proper  coat  of  lamellated  con- 
densed cellular  tissue,  which  by  detaching  inwards  its  pro- 
longations, keeps  the  parts  of  these  bodies  together,  and 
marks  out  their  divisions.  In  the  centre  of  the  renal  cap- 
sule, a cavity  may,  from  time  to  time,  be  found;  but,  accord- 
ing to  my  own  observations,  nothing  is  less  certain  than  its 
existence;  and,  in  the  opinion  of  Meckel,  when  found,  it  is 
the  result  of  cadaverous  decomposition.  In  the  foetus  it  con- 
tains a reddish  viscid  fluid,  which  seems  to  consist  in  a large 
share  of  albumen,  as  It  coagulates  with  alcohol;  in  children 
this  fluid  becomes  yellow;  in  adults  it  is  dark  brown;  and  in 
old  people  it  is  either  entirely  deficient,  or  in  a remarkably 
small  quantity. 

Of  the  Minute  Structure  of  the  Capsulse  Renales.  The 
arteries  of  these  bodies  come  from  the  emulgents,  from  the 
phrenics;  and  from  the  aorta.  The  veins  of  the  right  one  ter- 
minate in  the  cava  ascendens,  and  of  the  left  in  the  emulgent. 
Each  one  is  divisible  into  lobes,  and  by  a slight  maceration 
may  be  reduced  into  lobules  and  small  granulations.  The 

* This  opinion  has  recently  been  confirmed  in  a dissection  of  a fcetus, 
by  myself,  where  the  kidneys  being  absent  the  capsuls  renales  existed. 

VoL.  II.— 10 


74 


URINARY  ORGANS. 


external  part  is  rather  more  consistent  and  yellow  than  the 
internal.  The  granulations  seem  to  have  an  intimate  con^ 
nexion  with  the  veins,  as  they  are  easily  penetrated  by  fluid 
injections  from  the  latter. 

Reputed  excretory  ducts  for  these  bodies  have  been  found 
going  to  the  testicles,  to  the  pelvis  of  the  kidneys,  and  to 
the  thoracic  duct,  but  no  weight  is  now  attached  to  such 
assertions. 

Of  the  Bladder. 

The  Bladder,  {Vesica  Urinaria,)  the  reservoir  for  the 
urine,  is  placed  in  the  pelvis,  just  behind  the  symphysis  of 
the  pubes.  When  pressed  upon,  as  it  commonly  is,  by  the 
adjacent  viscera,  it  is  flattened  somewhat  before  and  behind; 
but,  removed  from  the  body  and  inflated,  it  is  an  elongated 
sphere  or  oval;  the  greatest  diameter  of  which  is  vertical,  in 
regard  to  the  linea  ilio-pectinea.  The  superior  end  of  the 
bladder  is  called  the  upper  fundus,  and  the  lower  end  the  infe- 
rior fundus;  the  latter  is  rather  more  obtuse  than  the  other; 
and  between  the  two  is  the  body.  The  neck  of  the  bladder 
is  its  place  of  junction  with  the  urethra.  The  form  of  the 
bladder  is  influenced  by  age  and  by  sex;  in  very  young  in- 
fants it  is  cylindroid,  and,  owing  to  the  smallness  of  the 
pelvis,  rises  up  almost  wholly  into  the  abdomen.  In  the 
adult  woman,  who  has  frequently  born  children,  it  is  nearly 
spherical,  has  its  greatest  diameter  transverse,*  and  is  more 
capacious  than  in  man. 

The  bladder  is  bounded  in  front  by  the  pubes,  above  by 
the  small  intestine,  behind  by  the  rectum,  and  below  by  the 
prostate  gland  and  the  vesiculse  seminales.  From  its  supe- 
rior end  there  proceeds  to  the  umbilicus  a long  conical  liga- 
ment, the  urachus,  which  is  placed  between  the  linea  alba 
and  the  peritoneum,  and  produces  a slight  elevation  or 
doubling  of  the  latter.  In  mankind  the  urachus  is  solid; 
some  very  rare  cases,  however,  are  reported  in  which  it  has 
been  hollow,  so  as  to  permit  the  urine  to  flow  through  it 
from  the  bladder.  This  vicious  conformation  has  generally 
been  attended  with  a congenital  obstruction  of  the  urethra,  t 

* H.  Cloquet,  Anat.  Descrip.  f S.abatier,  Anat.  vol.  iii.  p.  19. 


THE  BLADDER. 


75 


When  the  anterior  parietes  of  the  abdomen  are  put  upon 
the  stretch,  a semilunar  fold  of  the  peritoneum  is  seen  to 
proceed,  on  either  side  of  the  urachus,  from  the  lateral  sur- 
face of  the  bladder  almost  to  the  umbilicus.  These  folds 
contain,  in  their  loose  edge,  the  fibrous  remains  of  the  um- 
bilical arteries  of  the  foetus,  called,  subsequently  to  uterine 
life,  the  Round  Ligaments  of  the  bladder,  though  they  have 
little  or  no  influence  on  its  position.  The  bladder  is  also 
fixed  in  its  situation  by  the  pelvic  aponeurosis,  a membrane 
elsewhere  described  with  the  organs  of  generation. 

The  bladder  consists  of  four  coats:  the  Peritoneal,  the 
Muscular,  the  Cellular,  and  the  Mucous. 

The  Peritoneal  Coat  is  very  imperfect,  and  is  derived 
from  the  part  of  the  peritoneum  which  descends  ffom  the 
anterior  pai’ietes  of  the  abdomen  into  the  pelvis.  It  covers 
the  upper  and  the  posterior  face  of  the  bladder,  and  then 
passes  to  the  rectum,  by  sinking  down  between  these  two 
organs,  so  as  to  form  the  small  pouch  beneath  the  lower  fun- 
dus of  the  bladder;  the  apex  of  this  pouch  reaches  within 
an  inch  of  the  base  of  the  prostate.  The  upper  margin  of 
this  pouch  next  to  the  bladder  forms  a strong  horizontal 
doubling,  stretching  across  the  pelvis,  when  the  rectum  is 
empty,  and  is  on  a level  with  the  posterior  end  of  the  vesi- 
culse  seminales.  Being  connected  to  the  subjacent  muscular 
coat  by  a thin  lamina  of  loose  cellular  membrane,  the  peri- 
toneum may  be  dissected  off  without  difficulty.  In  consider- 
able distentions  of  the  bladder,  it  is  reflected  from  the  up- 
per end  of  the  latter  to  the  abdominal  muscles  in  a line 
much  above  the  pubes,  whereby  a good  opportunity  is  af- 
forded of  reaching,  with  an  instrument,  the  cavity  of  the 
bladder  without  injuring  the  peritoneum. 

The  Muscular  Coat  is  of  a thickness  intei’mediate  to  that 
of  the  stomach  and  of  the  oesophagus,  and  its  fibres  are  pale. 
They  pass  in  very  varied  directions,*  and  are  collected  into 
flattened  fasciculi,  leaving  interstices  between  them,  through 
which  the  internal  coat  is  occasionally  caused  to  protrude, 
in  strictures  and  other  obstructions  of  the  urethra.  These 

Santorini,  Septemd.  Tabul. 


7ti 


UKINAKV  ORGANS. 


fasciculi,  for  the  most  part,  arise  about  the  neck  of  the  blad- 
der, and  ascending  upwards,  before,  behind,  and  laterally, 
terminate  at  the  superior  fundus  in  the  base  of  the  urachus. 
Within  these,  which  may  be  considered  as  the  longitudinal 
fibres  of  the  bladder,  there  are  otliers  forming  a thinner  la- 
mina, whose  course  is  transverse,  or  oblique,  they  serve  to 
connect  the  preceding.  As  the  muscular  fibres  are  collect- 
ed at  the  neck  of  the  bladder,  and  at  the  urachus,  there  is, 
of  course,  an  increased  thickness  at  these  points. 

The  Cellular  Coat  consists  in  a close,  dense,  lamellated, 
and  fibrous  tissue,  very  extensible  and  difficult  to  tear.  It 
is  impervious  to  water,  adhci’es  closely  to  the  muscular  coat 
without  and  to  the  mucous  within,  so  as  to  form  a strong 
bond  of  union  between  them.  It  is  pervaded  by  many  ves- 
sels and  nerves,  which  it  conveys  to  the  mucous  coat. 

The  Mucous  Coat  is  also  called  the  villous,  but  is  much 
more  smooth  than  the  corresponding  one  of  the  stomach. 
It  is  white  with  a slight  tinge  of  red,  and  abounds  with  mu- 
cous follicles,  which,  though  small  and  scarcely  discernible 
in  a natural  state,  are  rendered  very  obvious  by  disease.  It 
stretches  with  much  facility,  but,  like  other  mucous  mem- 
branes, does  not  restore  itself  readily,  and  is  rather  thrown, 
in  the  contracted  state  of  the  bladder,  into  wrinkles  or  folds 
having  a diversified  course,  and  of  a fugitive  character,  as  they 
disappear  again  upon  the  next  distention.  It  is  veiy  vascular. 

The  internal  face  of  this  coat  presents,  at  its  inferior 
part,  the  following  appeai'ances : 

1.  ThQYesiQ,d\Tndj).^&  {Trigonus  Lieutaudi,  Trigone 
Vesicale)  is  placed  immediately  behind  and  below  the  neck 
of  the  bladder,  occupying  the  space  between  it  and  the  ori- 
fices of  the  ureters.  It  is  an  equilateral  triangle  of  an  inch 
in  length,  its  surface  is  smooth,  is  not  affected  materially  in 
extent  either  by  the  dilatation  or  the  contraction  of  the 
bladder,  and  is  elevated  so  as  to  be  sufficiently  distinct  and 
well  defined. 

2.  The  anterior  angle  of  the  triangle  looks  into  the  ori- 
fice of  the  urethra,  and  is  generally  so  elevated  that  it  has 
obtained  the  name  of  Uvula  Vesicse;  it  is,  however,  simply 
a projection  of  the  mucous  membrane  depending  upon  the 


THE  BLADDER. 


77 


subjacent  third  lobe  of  the  prostate;  which,  at  this  point,  is 
not  unfrequently  much  enlarged  in  the  aged,  and  then  pre- 
sents a great  difficulty  in  the  introduction  of  a catheter. 

3.  The  Orifices  of  the  ureters  form  the  posterior  angles 
of  the  triangle,  and  are  contracted  somewhat  below  the  size 
of  the  canals  themselves.  They  are  said,  by  Mr.  Charles 
Bell,*  to  be  furnished  each  one  with  a small  fasciculus  of 
muscular  fibres,  which  runs  backwards  from  the  orifice  of 
the  urethra,  just  beneath  the  lateral  margins  of  the  triangle, 
and,  in  its  contraction,  will  stretch  the  orifice  of  the  ureter 
so  as  to  permit  an  easy  passage  of  the  urine  into  the  blad- 
der. The  retrogradation  of  the  urine  is  prevented  by  the 
ureter  passing  obliquely,  for  six  or  eight  lines,  between  the 
muscular  and  mucous  coat;  there  is  something  also  in  the 
obliquity  of  the  orifice  itself  which  assists  in  this  effect;  as 
I have  ascertained  by  removing  the  muscular  coat  entirely, 
at  this  point,  and  dissecting  up  the  ureter,  notwithstanding 
which,  the  bladder,  when  inflated,  still  retained  its  con- 
tents. Where  the  ureter  penetrates  the  muscular  coat,  I 
have  in  several  instances  found  a layer  of  longitudinal  mus- 
cular fibres  enveloping  it  for  half  an  inch,  or  an  inch. 

4.  The  Inferior  Fundus  of  the  bladder  {bas-fond  of  the 
French)  is  a depression  of  the  general  concavity  of  the 
bladder,  of  about  six  lines  in  depth,  placed  between  the 
base  of  the  triangle,  and  the  posterior  side  of  the  bladder. 
In  the  erect  position,  calculus,  when  one  has  it,  lodges  there. 

5.  The  Internal  Orifice  of  the  neck  of  the  bladder,  re- 
sembles strongly  that  of  a Florence  flask,  modified,  how- 
ever, by  the  projection  of  the  uvula  vesicae,  which  makes 
it  somewliat  crescentic  below.  The  neck  of  the  bladder  pe- 
netrates the  prostate  gland,  but,  at  its  commencement,  is 
surrounded  by  loose  cellular  tissue  containing  a very  large 
and  abundant  plexus  of  veins,  t The  internal  layer  of  mus- 
cular fibres  is  here  transverse;  and  they  cross  and  intermix 
with  each  other  in  different  directions,  forming  a close  com- 
pact tissue,  which  has  the  effect  of  a particular  apparatus  for 

* Med.  Chir.  Ti-ans.  Vol.  III. 

f Mascagni,  Anat.  Univers.  Sti*.  prim.  tab.  spec.  Fig.  V. 


7« 


UIIINABY  ORGANS. 


retaining  the  urine,  and  is  called  Musculus  Sphincter  Ve- 
sicse  Urinariai.  Generally,  anatomists  have  not  considered 
this  structure  as  distinct  from  the  muscular  coat  at  large, 
but  Mr.  Charles  Bell,  of  London,  whose  reputation  as  an 
anatomist  is  well  established,  gives  the  following  account 
of  it:  “Begin  the  dissection  by  taking  off  the  inner  mem- 
brane of  the  bladder  from  around  the  orifice  of  the  urethra. 
A set  of  fibres  will  be  discovered  on  the  lower  half  of  the 
orifice,  which  being  carefully  dissected,  will  be  found  to 
run  in  a semicircular  form  round  the  urethra.  These  fibres 
make  a band  of  about  half  an  inch  in  breadth,  particularly 
strong  on  the  lower  part  of  the  opening,  and,  having 
mounted  a little  above  the  orifice  on  each  side,  they  dispose 
of  a portion  of  their  fibres  in  the  substance  of  the  bladder.  A 
smaller  and  somewhat  weaker  set  of  fibres  will  be  seen  to 
complete  their  coui'se,  surrounding  the  orifice  on  the  upper 
part;  to  these  sphincter  fibres  a bridle  is  joined,  which 
comes  from  the  union  of  the  muscles  of  the  ureters.”* 
That  a power  exists  in  the  neck  of  the  bladder  of  retaining 
completely  the  urine,  has  been  satisfactorily  demonstrated 
to  me  in  a case  of  fistula  in  perineo,  which  was  presented 
to  the  notice  of  Dr.  Physick  and  myself,  a few  years  ago.t 
Occasionally  there  exists  on  each  side  of  the  neck  of  the 
bladder,  passing  from  it  to  the  pubes,  a muscle  of  half  an 
inch  in  bz'eadth,  the  effect  of  which  is,  to  draw  the  neck  of 
the  bladder  towards  the  symphysis  pubis. 

As  the  urethra  of  the  male  performs  the  double  office 
of  conducting  botli  semen  and  urine,  it  will  be  described 
more  properly  along  with  the  organs  of  generation. 

The  Urine  has  a considerable  number  of  constituents,  the 
pi’oportion  of  which  varies  according  to  age,  health,  and 
other  circumstances.  Water  forms  about  nine-tenths  of 
it,  the  remainder  is  an  animal  matter  insoluble  in  alco- 
hol; uric  and  lactic  acids;  lactate  of  ammonia;  sulphate  of 
potash  and  of  soda;  hydrochlorate  of  soda  and  of  ammonia; 
phosphate  of  soda  and  of  lime;  fluate  of  lime. 

* Diseases  of  the  Urethra,  8cc.  p.  10.  Lonch  1820. 

f Chapman’s  Med.  and  Ph)'s.  Journal,  1824. 


BOOK  VI. 


Organs  of  Generation. 

CHAPTER  I. 

OF  THE  ORGANS  OF  GENERATION  IN  THE  MALE. 

The  Male  Organs  of  Generation  consist  in  the  Testicles 
and  in  the  Penis,  with  their  appendages;  or,  in  the  language 
of  some  anatomists,  in  the  Formative  and  in  the  Copulative 
Organs;  which  distinction  has  been  applied  to  both  sexes. 

SECT.  I. OF  THE  PENIS. 

The  Penis  {Membrum  Virile,  Mentula)  from  perform- 
ing two  offices;  one  of  which  is  the  conducting  of  urine  from 
the  bladder,  and  the  other  the  projection  of  semen  into  the 
female;  has  accordingly  a peculiarity  of  structure,  which 
allows  it  to  assume  a state  of  rigid  distention  or  of  collapse, 
according  to  the  exigencies  of  the  system.  Its  shape  is  al- 
most cylindrical,  but  terminating  in  front  by  an  obtusely 
pointed  extremity.  It  adheres  by  its  posterior  end  or  root 
to  the  bones  of  the  pelvis,  at  and  below  the  symphysis 
pubis. 

It  is  formed  by  common  integuments,  by  cellular  tissue, 
by  the  Corpus  Cavernosum,  and  by  the  Corpus  Spongiosum. 

The  skin  on  the  penis  is  more  thin  and  delicate  than  it  is 
on  most  other  parts  of  the  body,  and  is  furnished  with  a 
considerable  number  of  sebaceous  follicles  or  glands  about 
the  root  of  the  organ,  with  hairs  growing  from  the  centre 
of  them.  This  same  skin,  in  passing  to  the  abdomen  over 


80 


ORGANS  OP  GENERATION. 


the  pubes,  is  somewhat  protruded  by  a subjacent  deposite 
of  fat  and  cellular  matter,  causing  an  ajipearance  corres- 
ponding with  the  mens  veneris  of  the  female;  and  is  also 
generally  thickly  covered  with  short  curly  hair,  which,  as 
the  individual  advances  in  life,  proceeds  in  a pointed  direc- 
tion to  the  umbilicus.  The  skin  of  the  penis  is  but  loosely 
connected  to  the  organ,  so  that  it  slides  readily  backwards 
and  forwards,  and  by  its  elasticity  is  well  suited  to  the  va- 
rying states  of  erection  and  collapse.  At  the  anterior  ex- 
tremity it  is  thrown  into  a duplicature  or  fold,  the  Prepuce, 
{Preputium,)  the  internal  lamina  of  which  being  inserted 
circularly  into  the  penis,  some  distance  back  from  the  point, 
permits  a considei’able  portion  of  the  extremity  of  the  penis, 
called  the  Gians,  to  remain  uncovered  when  the  prepuce  is 
drawn  back.  The  under  middle  part  of  the  prepuce  is  at- 
tached to  the  extremity  of  the  glans  by  a vertical  longitudi- 
nal duplicature,  called  the  Frsenum,  which  extends  to  the 
orifice  of  the  urethra. 

The  skin  does  not  actually  stop  at  the  circumference  of 
the  glans,  but  is  continued  smoothly  over  it,  modified  how- 
ever so  much  in  its  structure,  as  to  be  much  more  adherent, 
soft,  delicate,  vascular,  and  sentient;  its  cuticle  is  a thin 
epithelium  readily  separated  by  maceration.  The  project- 
ing circular  and  oblique  shoulder  of  the  glans,  behind  which 
the  skin  becomes  firmly  joined  to  the  penis,  is  called  Coro- 
na glandis.  The  contracted  portion  behind  the  corona  is 
the  neck  {collum.)  On  the  surface  of  the  neck  and  the 
posterior  face  of  the  corona,  the  skin  is  furnished  with  an 
abundance  of  small  glandular  masses  or  follicles,  {Glandulse 
Odoriferx  Tysonii,)  which  secrete  the  thick  white  seba- 
ceous matter,  {smegma  prxputei,)  that  accumulates  when 
personal  cleanliness  is  not  attended  to. 

Tlie  penis,  in  addition  to  other  modes  of  attachment  to 
the  bones  of  the  pelvis,  is  fixed  by  the  Ligamentum  Sus- 
pensorium.  The  latter  is  a triangular  vertical  fibrous  la- 
mina, which  proceeds  downwards  from  the  symphysis 
pubis  to  the  dorsum  of  the  penis;  and,  according  to  Mr. 
Colies,  envelops  this  organ  to  the  glans,  forming  its  cellu- 


THE  PENIS. 


81 


lar  coat,  and  being  continued  into  the  fascia  superficialis  ab- 
dominis. Posteriorly  it  is  lost  insensibly  on  the  fascia  of 
the  thighs,  covering  the  adductor  muscles.  At  its  origin  it 
is  occasionally  furnished  with  muscular  fibres;  one  strongly 
marked  instance  of  which  has  been  presented  to  me  in  my 
own  dissections. 

The  Corpus  Cavernosum  of  the  penis,  forms  by  much 
the  most  considerable  portion  of  the  whole  organ.  Exter- 
nally it  is  a white  fibrous  membrane,  of  a dense  structure, 
enjoying  extensibility  and  an  extreme  degree  of  contracti- 
lity. Its  fibres  pass  for  the  most  part  longitudinally,  ex- 
cept about  the  root,  where  they  are  blended  with  the  peri- 
osteum of  the  bone,  and  with  the  tendons  of  the  muscles. 
This  coat  of  the  penis  is  occasionally  called  its  elastic  liga- 
ment. It  arises  by  two  conical  crura,  from  the  inter- 
nal face  of  the  crura  of  the  pubes  and  ischia  to  within  a 
little  distance  of  the  anterior  part  of  the  tuber  ischii.  At 
the  lower  part  of  the  symphysis  pubis  these  crura  join  and 
form  a body;  which,  when  stripped  of  its  connexions, 
resembles  two  cylinders  lying  along  side  of  each  other, 
united;  and  which  terminate  in  common  anteriorly,  by  a 
truncated  cone,  covered  obliquely  by  the  glans.  At  the 
posterior  part  of  the  corpus  cavernosum,  in  its  centre,  there 
is  a septum,  almost  complete,  also  of  the  same  elastic  sub- 
stance, which  separates  the  two  halves  from  each  other;  but 
anteriorly  this  septum  is  more  imperfect,  having  an  arrange- 
ment like  the  teeth  of  a comb,  whence  the  term  Septum 
Pectiniforme  has  been  given  it. 

In  tbe  middle  of  the  corpus  cavernosum  above  is  a lon- 
gitudinal depression  for  lodging  the  veins  of  the  penis,  and 
in  the  same  manner  there  is  another  below,  for  the  corpus 
spongiosum  urethrae.  The  cavity  of  this  membrane  is  filled 
by  a spongy  tissue,  that  arises  from  its  internal  face,  and  is 
formed  of  filaments  and  little  laminae;  they,  by  crossing  each 
other,  make  a multitude  of  cells,  which  have  a perfectly 
free  communication  with  one  another,  and  generally  are 
somewhat  occupied  by  blood.  A fine  injection  through  the 
VoL.  II.— 11 


S2  ORGANS  OF  GENERATION. 

artery  of  the  corpus  cavernosum  will  fill  these  cells'  and  re- 
turn through  the  veins;  from  which  cause  the  cells  may  be 
considered  as  intermediate  to  the  two  orders  of  vessels. 

The  Corpus  Spongiosum  Urethras  extends  from  ten  or 
twelve  lines  behind  the  junction  of  the  crura  of  the  corpus 
cavernosum,  to  the  anterior  extremity  of  the  penis.  Ex- 
ternally it  has  a coat  resembling  that  of  the  corpus  caver- 
nosum, except  that  it  is  thinner,  and  in  its  centre  is  the  ca- 
nal for  the  passage  of  urine.  Between  the  canal  and  the 
coat  is  a spongy  structure,  much  finer  than  that  of  the  cor- 
pus cavernosum,  and  though  the  cells  communicate  freely, 
still  they  have  the  appearance  of  convoluted  veins.  The 
corpus  spongiosum  is  not  of  equal  diameter  in  its  whole 
course,  for  its  commencement  in  the  perineum,  where  it  is 
pendulous,  is  enlarged  into  what  is  termed  a Bulb;  from 
this  it  diminishes  gradually  to  the  anterior  end,  where  it  is 
again  enlarged  into  the  glans  penis. 

The  Urethra  is  a canal,  whose  length  varies  according  to 
the  degree  of  erection  in  the  penis,  and  extends  from  the 
neck  of  the  bladder  to  the  extremity  of  the  glans.  It  has 
sevei’al  curvatures,  and  receives  in  its  course  the  ductus 
ejaculatorii,  the  excretory  duds  of  Couper’s  glands,  and 
the  mucous  lacunae  of  its  own  internal  membrane.  The 
first  part  of  this  canal  which  traverses  the  prostate  gland  is 
from  fifteen  to  eighteen  lines  in  length,  and  is  called  the 
Prostatic  Portion;  it  is  well  supported  by  this  body,  al- 
though its  own  sides  are  very  thin.  On  its  inferior  surface 
is  a doubling  which  constitutes  the  Verumontanum  or  Ca- 
put Gallinaginis.  On  either  side  of  the  caput  gallinaginis 
the  canal  of  the  urethra  is  depressed  into  something  like  a 
cul-de-sac,  where  are  to  be  found  the  lacunae  of  the  prostate 
gland. 

Between  the  Prostate  and  the  Bulb  is  the  Membranous 
part  of  the  urethra,  about  eight  or  ten  lines  long;  it  is  un- 
protected, except  by  a soft  covering,  which  seems  in  some 
measure  to  be  a mixture  of  gelatinous  matter  and  muscular 
fibre.  The  former  was  considered  by  Littre  as  a glandular 


THE  PENIS. 


83 


body  which  secreted  a viscid  humour  into  the  interior  of 
the  canal;  the  latter  probably  is  the  part  described  by  Win- 
slow as  the  inferior  prostatic  muscle;  which,  arising  on  each 
side  of  the  membranous  canal,  goes  to  be  inserted  into  the 
corresponding  branch  of  the  pubes  near  the  symphysis. 
The  membranous  part  of  the  urethra  does  not  get  into  the 
end  of  the  bulb,  but  penetrates  it  from  above,  half  an  inch 
or  more  occasionally,  from  its  extremity,  just  below  the 
junction  of  the  Corpora  Cavernosa. 

The  canal  varies  in  its  dimensions;  at  its  commencement, 
which  is  synonymous  with  the  neck  of  the  bladder,  it  is 
large:  it  then  contracts  at  the  back  of  the  caput  gallinaginis, 
and  immediately  enlarges  in  the  fore  part  of  the  prostate. 
The  membranous  part  is  small;  the  canal  then  enlarges  in 
the  bulb.  In  the  body  of  the  penis  the  canal  is  successive- 
ly diminished,  till  it  comes  almost  to  the  glans,  Avhen  it  is 
so  remarkably  enlarged  again  as  to  get  the  name  of  Fossa 
Navicularis;  it  terminates  finally  by  a short  vertical  slit  at 
the  extremity  of  the  glans. 

In  the  whole  length  of  the  canal  there  are  two  whitish 
middle  lines,  one  above,  and  the  other  below;  and  in  the 
membranous  and  spongy  portions,  excepting  the  fossa  na- 
vicularis, longitudinal  folds  of  the  lining  membrane  exist, 
which  are  efiaced  by  distention.  In  the  upper  part  of  the 
canal  there  are  a great  many  mucous  lacunas;^  Loder  has 
marked  about  sixty-five;  there  is  one  particularly  large  in 
the  upper  surface  of  the  fossa  navicularis,  which,  it  is  said, 
has  stopped  the  point  of  a bougie  and  been  mistaken  for 
stricture,  t 

Mr.  Shaw  has  described  a set  of  vessels  immediately  on 
the  outside  of  the  internal  membrane  of  the  urethra;  which, 
when  empty,  are  very  similar  in  appearance  to  muscular 
fibres.  He  says,  he  has  discovered  that  these  vessels  form 
an  internal  spongy  body,  which  passes  down  to  the  mem- 

* Tabula  Anat. 

f Sir  Everard  Home  has  lately  communicated  to  the  Royal  Society  a 
highly  interesting  paper  on  tlie  structure  of  the  lining  membrane  of  the 
urethra.  From  his  microscopial  observations  he  is  induced  to  think  that 
it  is  musculai’. 


S4 


ORGANS  OF  GENERATION. 


branous  part  of  the  urethra,  and  forms  even  a small  bulb 
there.*  His  preparation,  being  a quicksilver  injection  of  the 
part,  is  certainly  a very  satisfactory  demonstration  of  its 
existence,  yet,  in  my  own  observations,  where  the  blow- 
pipe has  been  resorted  to,  it  has  rather  appeared  to  me  to 
be  the  cellular  membrane  connecting  the  canal  of  the  ure- 
thra with  the  corpus  spongiosum. 

The  arteries  of  the  penis  come  from  the  internal  pudic; 
some  of  its  veins  follow  the  course  of  the  arteries,  and 
others  collect  into  the  vena  magna  ipsius  penis;  the  nerves 
come  from  the  internal  and  external  pudics. 

SECT.  II. OF  THE  MUCOUS  GLANDS  AND  APPARATUS. 

The  Seminal  Vesicles  ( Vesicxdse  Seminales)  are  two  con- 
voluted tubes,  one  on  each  side,  two  inches  in  length,  placed 
on  thelower  fundus  of  the  bladder,  between  it  and  the  rectum' 
and  behind  the  prostate  gland.  At  their  anterior  extremities 
they  approach  very  nearly  to  each  other,  being  only  separa- 
ted by  the  intervention  of  thevasa  deferentia.  They  are  fixed 
to  the  bladder,  and  surrounded  by  a thick  mass  of  adipose 
and  cellular  matter,  with  many  blood  vessels,  principally 
veins,  passing  through  it. 

When  inflated  and  dried,  they  present  the  semblance  of 
cells,  but  are  in  fact,  long  tubes;  which,  by  being  convoluted, 
are  reduced  to  the  apparent  dimensions  mentioned.  When 
dissected  and  stretched  out,  they  are  four  or  five  inches  long 
by  three  lines  in  diameter. 

There  are  also  several  pouches  on  each  side  of  the  long 
tube  which  increase  the  number  of  cells.  The  convolutions 
are  preserved  by  the  intermediate  cellular  tissue.  These 
bodies  consist  of  two  coats:  an  external,  which  is  fibrous 
and  cellular;  and  an  internal,  which  is  mucous,  being  a con- 
tinuation of  lining  membrane  of  the  urethra.  They  are 
commonly  filled  by  a drab-coloured  thick  fluid,  supposed  to 
be  a mixture  of  the  semen,  with  their  own  proper  secretion, 
though,  of  this,  Mr.  Hunter  doubted,  t The  excretory  duct 

* Med.  Chir.  Trans,  vol.  x. 

•f-  Obseirations  on  the  Animal  CRconomy. 


MUCOUS  GliANDS. 


85 


uf  each  vesicle  is  about  a line  and  a half  long,  when  it  joins 
in  the  subtance  of  the  prostate  with  the  vas  deferens  of  the 
same  side;  a common  canal  (Ductus  Ejaculatorius)  is  thus 
formed,  which  runs  parallel  with  its  fellow,  below  the  ure- 
thra.^ 

The  Ductus  Ejaculatorius  is  about  eight  or  ten  lines  long, 
and  opens  by  an  oblong  orifice,  at  the  lateral  anterior  face 
of  the  Caput  Gallinaginis:  it  is  larger  behind  than  before, 
which  gives  it  a conical  shape,  and  allows  fluids  injected  to 
pass  freely  from  the  vas  deferens  to  the  vesicula,  and  the  re- 
verse. 

The  Prostate  Gland  {Glandula  Parastata^)  is  a body 
about  the  size  and  form  of  a horse  chestnut,  fixed  on  the 
neck  of  the  bladder,  and  penetrated  by  the  urethra,  which 
traverses  it  much  nearer  its  superior  than  its  inferior  sur- 
face. The  base  of  it  is  turned  backwards,  and  the  point 
forwards;  its  inferior  surface  rests  upon  the  rectum,  and  its' 
sides,  in  the  distentions  of  this  organ  by  faeces,  are  over- 
lapped by  it.  The  Prostate  has,  posteriorly,  a notch  in  its 
centre,  which  divides  it  into  two  lateral  lobes,  and  by  rais- 
ing the  Vesiculae  Seminales,  we  see  where  their  excretory 
ducts  penetrate  the  gland,  and  separate  from  the  body  of  it 
the  little  tubercle,  to  which  Sir  Everard  HomeJ  has  parti- 
cularly called  the  attention  of  the  profession,  and  considered 
as  a Third  Lobe,  it  being  certain  that  it  is  frequently  the 
seat  of  disease  and  tumefaction. 

On  the  under  surface  of  the  canal  formed  in  the  prostate, 
by  the  urethra,  is  the  oblong  elevation  called  the  Verumonta- 
num,  or  Caput  Gallinaginis.  It  commences  a little  in  front 
of  the  uvula  vesicse,  and,  being  broader  and  higher  behind, 
comes  to  a point  very  gradually  before;  it  is  about  eight  or 

* Lately,  in  a dissection  executed  at  the  university  by  Dr.  TogTio,  a mus- 
cle was  found  on  the  inferior  surface  of  the  seminal  vesicles  arising  from  tiie 
prostate  gland,  and  inserted  into  them.  This  is  said  to  be  a common  ar- 
rangement in  some  animals. 

f From  I'sijitti,  sto. 

T Diseases  of  Prostate. 


ORGANS  OF  GENERATION. 


Sti 

ten  lines  long.  Along  the  posterior  part  of  this  ridge  is  a long 
cleft,  being  the  orifice  of  a lacuna  first  observed  by  Mor- 
gagni; and  in  front  of  it  are  the  orifices,  bordering  upon  each 
other,  of  the  ductus  ejaculatorii. 

The  prostate  consists  in  a condensed,  white,  extensible, 
though  easily  lacerated  fibrous  cellular  tissue,  within  which 
are  placed  a great  number  of  mucous  follicles,  that  have  from 
eight  to  twelve  ducts,  or,  according  to  Loder,  from  thirty- 
two  to  forty-four,  passing  obliquely  forwards,  and  termi- 
nating in  the  urethra,  as  stated,  at  each  side  of  the  urethral 
crest,  or  caput  gallinaginis.  The  fluid  secreted  is  thick, 
ropy,  white,  and  semitransparent,  in  a healthy  state.  The 
prostate  is  surrounded  by  a fibrous  capsule,  to  be  de- 
scribed. 

The  lacunas  of  the  third  lobe  penetrate  the  coats  of  the 
bladder,  behind  the  caput  gallinaginis. 

Of  the.  Glands  of  Coupes'. — These  glands  are  also  in- 
tended for  the  secretion  of  mucus,  or  a fluid  very  much  like 
it,  into  the  canal  of  the  urethra.  They  are  two  in  number, 
one  on  each  side,  and  are  situated  in  advance  of  the  pros- 
tate, between  the  laminae  of  the  triangular  ligament,  at  the 
point  where  the  bulb  of  the  urethra  adheres  to  it.  Com- 
monly they  are  about  the  size  of  a garden  pea,  but  not  un- 
frequently  much  smaller,  and  in  some  instances,  cannot  be 
found  at  all,  which  induced  Heister  to  declare,  that  he  had 
searched  for  them  fruitlessly.  They  are  yellowish,  hard, 
and  consist  of  several  lobules  united  together.  Each  one 
has  an  excretory  duct  that  receives  readily  a bristle,  and 
passes  obliquely  forwards,  between  the  corpus  spongiosum 
and  the  canal  of  the  urethra,  to  terminate  in  an  oblique  ori- 
fice in  the  latter,  about  an  inch  distant  from  the  gland. 

One  or  more  glands,  of  the  same  description,  are  occa- 
sionally found  just  in  front  of  Couper’s.  They  also  dis- 
charge their  secretion  into  the  adjacent  part  of  the  urethra. 
In  my  own  dissections  I have  not  met  with  them. 


THE  TESTICLES. 


87 


SECT.  III. OF  THE  TESTICLES. 

The  Testicles  ( Testes,  Didymi)  are  two  in  number,  one 
on  either  side  of  the  scrotum.  From  being  the  seat  of  the 
secretion  of  sperm  or  the  male  prolific  liquor,  their  function 
is  of  the  lirst  importance  in  the  act  of  generation.  They 
are  of  an  oblong  oval  form,  somewhat  compressed  laterally; 
and  present  their  edges  forwards  and  backwards.  From 
being  suspended  near  the  middle  of  their  posterior  edge  by 
the  spermatic  chord,  the  upper  end  points  somewhat  for- 
wards, while  the  lower  one  is  directed  in  the  same  degree 
backwards.  They  are  about  an  inch  and  a half  long,  by 
one  inch  in  breadth,  and  eight  or  nine  lines  in  thickness. 
They  are  of  equal  size  generally,  but  in  case  of  a difference 
it  is  in  favour  of  the  right;  the  latter  is  also  remarkable  for 
being  suspended  higher  than  the  left,  a feature  in  ancient 
statuary  so  universal,  as  to  prove  the  vigilance  and  accuracy 
of  the  sculptors  of  those  days,  in  regard  to  the  proportions 
and  peculiarities  of  the  human  form. 

The  testicle  is  enveloped  by  several  tunics;  they  are  the 
scrotum,  the  dartos,  the  tunica  vaginalis,  and  the  tunica  al- 
buginea. 

The  Scrotum  is  merely  a continuation  of  the  common 
skin  from  the  inner  side  of  the  thighs,  the  perineum,  and 
the  penis,  and  is  common  to  the  two  testicles.  It  is  a 
symmetrical  bag,  and  the  two  halves  are  marked  off  from 
each  other  by  a middle  line  or  elevation  of  the  skin  called 
the  Raphe,  which  begins  in  the  perineum  at  the  anus,  and, 
winding  around  the  scrotum,  is  continued  along  the  under 
surface  of  the  penis  to  the  prepuce. 

The  skin  of  the  scrotum  is  thin,  darker  than  elsewhere, 
but  has  a thick,  strong  epidermis;  it  has  many  sebaceous 
follicles  in  it,  and  is  sparingly  furnished  with  hair.  It  is 
very  extensible,  as  manifested  in  fatigue,  and  by  hydrocele; 
and  may  be  contracted  again  so  as  to  draw  the  testicles  close 
under  the  pubes,  though  for  the  latter  power  it  principally 
depends  upon  the  subjacent  coat.  Its  surface  is  covered 


8S 


ORGANS  OF  GENERATION. 


with  wrinkles,  for  the  most  part  transverse,  and  ending  at' 
the  raphe;  they  are  effaced  during  its  great  distentions  in 
hernia  and  dropsy,  and  then  it  has  a smooth  shining  sur- 
face. 

The  Darios  is  placed  within  the  scrotum,  and  forms  two 
distinct  sacs  or  tunics,  one  for  each  testicle.  It  arises  from 
the  inferior  margins  of  the  crura  of  the  ischia  and  of  the 
pubes,  and  lines  the  scrotum  till  it  I’eaches  the  raphe;  it  is 
then  reflected  upwards  to  form  the  partition  between  the 
testicles,  {septum  scroti,)  and  terminates  at  the  corpus 
spongiosum  urethrae.  This  membrane,  according  to  the 
observations  of  MM.  Chaussier,  Lobstein,  and  Breschet,*' 
does  not  exist  in  the  scrotum  till  the  descent  of  the  testicle, 
and  then  appears  to  be  an  expansion  of  the  gubernaculum 
testis. 

It  receives  a considerable  number  of  blood  vessels,  which, 
owing  to  the  thinness  of  the  skin,  may  be  seen  in  the  living 
body  I'amifying  through  its  substance:  its  general  appear- 
ance is  therefore  reddish.  It  is  destitute  of  fat,  and  consists 
in  long  fibres  much  matted  together,  and  passing  in  every 
direction:  they  are  easily  separated  by  distention  with  air 
or  water,  and  by  slight  maceration.  Its  powers  of  contrac- 
tion are  exceedingly  well  marked  upon  the  application  of 
cold  to  the  scrotum,  from  which  cause,  it  has  been  consi- 
dered by  many  anatomists  as  muscular;  the  only  distinct 
evidences,  however,  which  I have  met  with  of  a resemblance 
to  the  latter,  have.been  found  generally  on  its  posterior  face, 
near  the  perineum,  t From  its  equivocal  character,  J.  F. 
Meckel  has  very  ingeniously  suggested  that  it  forms  the  tran- 
sition from  cellular  to  muscular  tissue,  and  that  there  exists 
between  it  and  other  muscles  the  same  relation  that  there 
is  between  the  muscles  of  the  superior  and  of  the  inferior 
orders  of  animals.  Among  the  latter  the  fibrous  structure  is 
indistinctly  marked,  and  is  masked  by  gelatine;  an  element 

* Dictionnaire  des  Sciences  Med.  tome  VIII. 

f Since  the  first  edition  I have  dissected  one  subject,  (Januarj'’,  1830,) 
where  the  fibres  were  evidently  muscular,  though  interwoven. 


THE  TESTICLES. 


89 


of  the  cellular  tissue  which  envelops  and  conceals  the 
fibrine,  an  element  of  the  muscular  tissue. 

The  fibres  of  the  cremaster  muscle,  which  are  next  in 
order,  form  a very  imperfect  covering  to  the  testicle,  and 
belong  rather  to  the  spermatic  chord:  what  remains  to  be 
said  concerning  them  will  be  more  properly  introduced 
into  the  account  of  the  latter.  The  cellular  substance 
that  connects  the  dartos  and  the  cremaster  with  the  tunica 
vaginalis  forms  a compact  and  perfect  lamina,  sometimes 
spoken  of  as  the  TWinica  Vaginalis  Communis  Testis. 
There  is  one  for  each  testicle,  which  it  surrounds  entirely, 
as  well  as  its  chord,  and  connects  the  chord  to  the  margins 
of  the  abdominal  rings  as  stated  in  the  account  of  them. 
At  its  upper  end  it  is  continuous  with  the  cellular  substance 
that  unites  the  peritoneum  to  the  parietes  of  the  abdomen,  as 
may  be  proved  by  inflating  it,  when  the  air  will  penetrate 
accordingly  through  the  abdominal  canal. 

The  Tunica  Vaginalis  was  originally  a process  of  pe- 
ritoneum, communicating  with  the  cavity  of  the  latter 
through  the  abdominal  canal;  but,  in  the  adult,  it  appears 
as  a complete  and  distinct  sac.  As  it  is  very  rigidly  com- 
parable to  a double  night-cap  drawn  over  the  head,  we  ac- 
cordingly find  that  the  testicle,  along  with  the  epididymis, 
is  pushed  into  it  from  behind.  That  portion  of  the  tunica 
vaginalis  which  is  in  contact  with  the  testicle,  or  rather  with 
the  tunica  albuginea,  adheres  so  closely  that  it  cannot  be 
separated  except  very  partially,  and  in  shreds;  but  it  may 
be  detached  easily  from  the  epididymis,  with  the  convolu- 
tions of  which  it  is  in  immediate  contact.  This  sac  is 
longer  and  larger  than  the  testicle  itself,  from  which  cause 
it  ascends  for  several  lines  above  the  superior  end  of  the 
gland,  and  the  free  part  hangs  loosely  about  it.  Its  cavity 
may,  with  but  little  force,  be  injected  so  as  to  hold  an  ounce 
or  two  of  fluid. 

This  membrane  is  smooth  and  polished  on  the  surface 
forming  its  cavity,  and  contains  a small  quantity  of  synovial 
VoL.  II.— 12 


90 


ORGANS  OP  generation. 


halitus,  which  allows  the  opposed  surfaces  to  glide  freely 
upon  one  another.  Its  exterior  connexion  with  the  dartos 
is  so  slight  that  it  may  be  withdrawn  without  dissection, 
with  the  exception  of  an  adhesion  at  the  lower  end  of  the 
testis,  arising  from  the  remains  of  the  gubernaculum : in 
such  case,  however,  it  still  continues  to  be  invested  by  the 
tunica  vaginalis  communis,  from  which  it  can  only  be  re- 
moved by  a special  dissection. 

The  Tunica  Albuginea  is  the  proper  coat  of  the  testicle, 
is  in  immediate  contact  with  its  glandular  structure,  and 
serves  to  maintain  its  shape,  as  well  as  to  protect  it  from 
pressure.  From  its  internal  surface  proceed  many  mem- 
branous, horizontal  fibres,  which  form  partial  partitions 
of  its  cavity  and  incline  towards  its  posterior  part,  where 
they  terminate  in  a longitudinal  projection,  called  Corpus 
Highmorianum.  The  latter  is  of  a prismatic  shape,  some- 
what broader  above  than  below,  and  is  but  of  little  conse- 
quence, except  that  it  was  once  erroneously  supposed  to  be 
a sinus  into  which  the  seminiferous  tubes  discharged.  The 
albuginea  is  perforated  by  several  foramina  along  its  poste- 
rior margin,  where  there  is  a deficiency  of  tunica  vaginalis, 
for  the  passing  of  excretory  ducts  and  blood  vessels. 

This  membrane  is  dense,  strong,  white,  and  fibrous,  re- 
sembling in  structure  the  tunica  sclerotica  of  the  eye,  and 
the  dura  mater  of  the  brain. 

Of  the  Minute  Structure  of  the  Testicle.  * — The  glan- 
dular portion  of  the  testicles  consists  in  a congeries  of  con- 
voluted tubes  ( Tuhuli  Seminiferi)  amounting  to  300,  ac- 
cording to  Dr.  Munro;  and  whose  aggregate  length  is  5208 
feet;  the  diameter  of  each  one  does  not  exceed  one  two- 
hundredth  part  of  an  inch,  and  its  length  is  somewhat  short 
of  seventeen  and  a half  feet.  These  tubes  form  convolu- 
lutions  or  hanks,  the  threads  of  which  are  serpentine,  very 

* Hunter,  Med.  Comment,  p.  1,  1777.  Albinus,  Acad.  Annot.  Lib.  ii. 
Loder,  Tab.  Anat.  Euysch,  Thes.Anat.  iv.  Haller,  Op.  Min.  tom.  ii.  Alcx- 
Munro,  de  Testibus,  Ed.  1755. 


THE  TESTICLES. 


91 


much  like  the  thi’ead  of  a ravelled  stocking;  and  are  held 
together  by  a delicate  cellular  substance  easily  softened  by 
maceration.  Each  tube  forms  of  itself  a hank  or  lobule, 
which  is  kept  distinct  from  the  adjacent  ones  by  the  parti- 
tions of  the  albuginea,  and  may  be  easily  picked  out  from 
them.  Their  extreme  tenuity  and  delicacy  of  structure 
cause  them,  when  well  macerated,  drawn  out  with  a pin, 
and  then  suspended  in  water,  to  resemble  a tangled  skein 
of  fine  silk. 

The  tubuli  seminiferi  finally  terminate  in  straight  tubes, 
called  the  Vasa  Recta,  which  unite  near  the  centre  of  the 
testicle,  in  a somewhat  complicated  arrangement,  obtaining 
the  name  of  Rete  Vasculosum  Testis.  From  the  latter 
there  proceed  from  twelve  to  eighteen  ducts  ( Vasa  Effe- 
rmtici)  which  go  upwards  and  backwards  to  penetrate  the 
corpus  highmorianum  and  the  tunica  albuginea.  Each  of 
these  vasa  efferentia  is  then  convoluted  upon  itself  into  a 
conical  body,  called  Conus  Vasculosus,  which  presents  its 
base  backwards.  Each  cone  at  its  base  has  its  tube  en- 
tering successively  into  the  tube  of  which  the  Epididymis 
is  formed. 

Notwithstanding  the  extreme  tenuity  of  these  several 
arrangements  in  the  excretory  ducts  of  the  testicle,  they 
may  be  entirely  filled  with  quicksilver  from  the  vas  de- 
ferens; but  the  task  is  one  of  great  difficulty,  and  rarely  suc- 
ceeds. 

The  Epididymis  is  the  prismatic  arch  which  rests  verti- 
cally on  the  back  of  the  testicle,  and  adheres  to  it  by  the 
reflection  of  the  tunica  vaginalis.  It  is  enlarged  at  both 
ends,  the  upper  of  which  being  formed  by  the  Coni  Vascu- 
losi,  is  called  the  Globus  Major,  and  the  lower  enlargement 
is  the  Globus  Minor.  It  is  formed  of  a single  convoluted 
tube,  of  the  fourth  of  a line  in  diameter.  After  this  tube 
has  got  to  the  lower  end  of  the  globus  minor  it  becomes  less 
convoluted,  enlarges,  turns  upwards  on  the  inner  side  of 
the  epididymis  and  obtains  the  name  of  Vas  Deferens.  Be- 
fore it  reaches  the  top  of  the  epididymis  it  has  become  per- 
fectly straight,  or  alm.ost  so.  There  is  a blind  duct  which 


ORGANS  OF  GENERATION. 


begins  at  the  top  of  the  epididymis  and  terminates  below: 
the  object  of  it  is  not  understood. 

Of  the  Spermatic  Chord. 

The  Spermatic  Chord  is  a fasciculus  of  about  half  an  inch 
in  diameter,  which  may  be  felt  very  readily  through  the 
skin  of  the  scrotum,  passing  from  the  upper  end  of  the  tes- 
ticle to  the  external  abdominal  ring.  It  is  formed  by  the 
Vas  deferens;  the  Spermatic  Artery  and  Veins;  the  Lym- 
phatics of  the  Testicle;  and  the  Nerves;  all  being  covered 
in  by  the  Tunica  Vaginalis  Communis,  and  by  the  Cremas- 
ter Muscle. 

The  Cremaster  Muscle,  also  called  the  tunica  elythroi- 
des,*  being  derived  from  the  internal  oblique  and  the  trans- 
verse muscle  of  the  abdoment  forms  a very  complete  enve- 
lope to  the  chord  from  the  abdominal  ring  to  the  testicle. 
But  when  it  reaches  the  latter  its  fibres  spread  out  and  be- 
come indistinct  upon  the  tunica  vaginalis  communis,  as  they 
there  consist  in  small,  pale,  scattered  fasciculi,  many  of  which 
terminate  insensibly,  while  others  form  on  the  front  of  the 
tunica  vaginalis  loops,  having  their  convexities  downwards. 
This  muscle  draws  the  testicle  upwards,  an  action  very  dif- 
ferent from  the  corrugation  of  the  scrotum. 

The  Vas  Deferens,  or  the  proper  excretory  duct  of  the 
testicle,  is  a white  tube  of  about  a line  and  a half  in  diame- 
ter, and  has  a cartilaginous  feel.  Its  parietes  are  thick,  as 
its  cavity  will  not  receive  a body  larger  than  a bristle,  with- 
out being  put  upon  the  stretch.  It  traverses  a long  space, 
and  in  doing  so,  first  passes  at  the  back  of  the  chord  from 
its  commencement,  to  the  internal  abdominal  ring;  having 
reached  the  latter,  it  then  abandons  the  spermatic  artery 
and  vein,  and  dipping  into  the  pelvis,  by  the  side  of  the 


■*  EAii7f«y,  a sheath. 


t Sec  Abdominal  Muscles, 


THE  TESTICLES. 


93 


bladder,  goes  between  the  lower  fundus  of  the  latter  and  the 
ureter.  It  then  converges  towards  its  fellow,  along  the  un- 
der extremity  of  the  bladder,  at  the  inner  margin  of  the 
vesicula  seminalis,  of  the  same  side,  and  finally  terminates 
in  the  urethra  near  the  neck  of  the  bladder.  ‘ About  two 
and  a half  inches  from  its  termination  it  enlarges  and  be- 
comes somewhat  tortuous. 

This  duct  consists  of  two  coats,  the  external  one  is  hard, 
compact,  and  occasionally  fibres  are  seen  in  it,  but  its  struc- 
ture is  not  very  evident,  and  is  peculiar.  The  internal  is  a 
mucous  membrane. 

For  the  description  of  the  remaining  portions  of  the  chord, 
see  Spermatic  Artery,  Vein,  Lymphatics,  and  Plexus  of 
Nerves. 

The  Testicles  undergo  a remarkable  change  in  their  posi- 
tion, from  the  earliest  development  of  their  rudiments  to  the 
perfect  foetal  state.  They  are  not  formed  in  the  scrotum, 
but  in  the  abdomen  just  below  the  kidneys;  from  which  po- 
sition they  are  gradually  transferred.  About  the  middle  of 
the  third  month  of  gestation  they  are  two  lines  long,  and 
placed  behind  the  peritoneum,  to  which  they  loosely  adhere. 
The  vas  deferens  then,  instead  of  rising  up  on  the  side  of  the 
epididymis,  goes  straight  down  into  the  pelvis.  At  this  peri- 
od may  be  seen  the  gubernaculum  testis,  discovered  by  J. 
Hunter,*  which  becomes  more  distinct  in  a few  weeks  after- 
wards, and  assumes  a triangular  appearance.  This  guberna- 
culum has  the  office  of  drawing  the  testicle  down  into  the 
scrotum;  its  point  commences  in  the  upper  part  of  the  latter, 
somewhat  below  the  external  abdominal  ring;  it  passes 
through  the  abdominal  canal,  ascends  upon  the  iliacus  inter- 
ims muscle,  and  is  attached  by  its  base  to  the  inferior  end 
of  the  testicle.  In  front  of  the  gubernaculum  a process, 
or  small  pouch  of  peritoneum,  passes  through  the  abdo- 
minal canal  to  the  upper  part  of  the  scrotum.  By  the  con- 
traction of  the  gubernaculum,  the  testicle  is  brought,  about 
the  seventh  or  eighth  month,  into  the  scrotum,  by  sliding 


* Med,  Comment,  Lond,  1777. 


ORGANS  OF  GENERATION. 


i)4 

down  behind  the  pouch.  The  lower  end  of  the  pouch  at 
which  the  testicle  is  finally  arrested  becomes  the  tunica  va- 
ginalis testis. 

As  soon  as  the  testicle  has  reached  the  scrotum,  the  neck 
of  the  pouch  has  a tendency  to  close  and  to  become  oblitera- 
ted, which  is  commonly  accomplished  at  the  period  of  birth; 
yet  itsometimes  remains  open  for  a longer  time,  and  becomes 
the  occasion  of  congenital  hernia.  Very  generally,  at  birth, 
the  orifice  of  the  pouch  will  receive  the  end  of  a probe  to  the 
depth  of  a line  or  two;  but  all  below  is  perfectly  closed,  and 
has  its  structure  so  condensed  and  altered  that  no  one,  from 
a view  of  it  alone,  would  suppose  that  the  cavity  of  the  tu- 
nica vaginalis  had  ever  communicated  with  that  of  the  pe- 
ritoneum, t 

SECT.  IV. — OF  THE  MUSCLES  AND  FASCIA  OP  THE 
PERINEUM. 

Perineal  Fascia. 

The  Perineal  Fascia  is  placed  just  beneath  the  skin  of  the 
perineum,  and  covers  the  muscles.  It  occupies  nearly  all 
the  space,  between  the  anus  and  the  posterior  margin  of  the 
scrotum,  and  between  the  rami  of  the  pubes  and  the  ischium 
on  each  side;  it  is  very  firmly  fixed  to  these  bones,  and  is 
gradually  blended  with  the  cellular  substance  of  the  poste- 
I’ior  part  of  the  scrotum.  This  fascia  is  rather  thin,  but,  in 
case  of  a rupture  of  the  posterior  part  of  the  urethra,  prevents 
the  urine  from  showing  itself  in  the  perineum,  and  drives 
it  into  the  cellular  structure  of  the  scrotum.  In  abscesses  of 
the  perineum,  it  also  prevents  the  fluctuation  from  being 
very  evident. 

The  explanations  and  anatomy  of  this  process  have  been  treated  at  large 
in  the  following  works: 

Girardi,  Tabul.  II.  adj.  Septemd.  Tab.  Santorini. 

Hunter,  Observations  on  certain  parts  of  the  Animal  (Economy.  W.  Hun- 
ter, Med.  Commentaries. 

Edward!  Sandifort,  Opusc.  Anat. 

Wrisberg  Comment.  Medici  Physiolog.  &c. 


MUSCLE^  AND  FASCIA  OP  THE  PERINEUM. 


95 


The  Musculus  Erector  Penis, 

Is  so  situated  as  to  cover  the  whole  of  the  crus  of  the 
penis  which  is  not  in  contact  with  the  bony  margin  of  the 
pelvis.  It  arises,  therefore,  tendinous  and  fleshy,  from  the 
anterior  part  of  the  tuber  ischii;  its  fleshy  fibres  adhere  to 
the  internal  and  external  margins  of  the  rami  of  the  pubes 
and  ischium,  and  proceed  upwards;  just  before  the  union 
of  the  crura  of  the  penis,  they  end  in  a flat  tendon  which 
is  lost  on  the  side  of  the  elastic  membrane  of  the  penis.* 

Its  use  is  not  well  understood. 

The  Musculus  Accelerator  Urinse, 

Lies  on  the  bulb  and  back  part  of  the  corpus  spongiosum 
urethrae;  it  is  a thin  muscle  consisting  of  oblique  fibres. 

It  arises  by  a pointed  production  from  the  side  of  the 
body  of  the  penis;  its  origin  is  continued  obliquely  across 
the  inferior  surface  of  the  crus  penis,  where  the  latter 
begins  to  form  the  body  of  the  penis.  It  arises  also  for  an 
inch  from  the  inner  side  of  the  ramus  of  the  pubes,  between 
the  crus  penis  and  the  triangular  ligament  of  the  urethra. 
The  muscles  of  the  opposite  sides  are  inserted  into  one  ano- 
ther by  a white  line,  which  marks  the  middle  of  the  bulb 
of  the  urethra;  and  by  a point,  into  the  anterior  extremity 
of  the  sphincter  ani,  where  they  are  joined  by  the  transversi 
perinei. 

In  order  to  see  the  origin  of  these  muscles  very  distinct- 
ly, separate  them  from  each  other  in  the  middle  line,  and 
dissect  them  from  the  corpus  spongiosum.  Cut  transvei'sely 
through  the  corpus  spongiosum  about  three  inches  before 
the  triangular  ligament,  and  dissect  it  clearly  from  the  cor- 
pus cavernosum,  turning  it  downwards  so  that  it  may  hang 
by  the  membranous  part  of  the  urethra.  By  putting  the 
two  acceleratores  on  the  stretch,  it  will  be  seen  that,  besides 
the  origins  mentioned,  they  arise  also  from  each  other  by  a 

* The  late  Dr.  Lawrence  informed  me  that  he  had  frequently  found  mus- 
cvdar  fibres  between  the  bone  and  the  crus  penis. 


96 


ORGANS  OF  GENERATION. 


tendinous  membrane  that  is  interposed  between  the  corpus 
spongiosum  and  cavernosum;  so  that  they  literally  surround 
the  bulb  of  the  urethra,  constituting  a complete  sphincter 
muscle  for  it.  This  account  of  the  accelerator  urinae  is  pe- 
culiar to  myself.  I have  adopted  it  from  the  sti’ong  ana- 
logy between  it  and  the  sphincter  vaginae. 

These  two  muscles  are  considered  by  M.  Chaussier  as 
forming  but  one;  in  that  case  its  origin  will  be  reversed, 
and  commence  in  the  middle  line  of  the  perineum  instead 
of  terminating  there.  As  this  muscle  and  the  erector  pe- 
nis touch  by  their  contiguous  faces,  it  is  difficult  to  get  into 
the  membranous  part  of  the  urethra  in  lithotomy  without 
cutting  through  the  muscular  fibres  of  one  or  the  other. 

It  propels  the  urine  and  semen  forward. 

The  Musculus  Transversus  Perinei, 

As  its  name  implies,  passes  directly  across  the  perineum; 
it  arises  from  the  inner  side  of  the  ischium,  just  at  the  ori- 
gin of  the  erector  penis,  and  is  inserted  where  the  sphincter 
ani  and  acceleratores  join. 

I have  observed  that  when  the  lower  part  of  the  accelera- 
tores was  extended  much  below  their  usual  line,  and  strong- 
ly developed,  that  the  transversus  was  very  irregular  in 
its  origin  and  course;  consisting  frequently  of  a few  fibres 
which  did  not  deserve  the  name  of  a distinct  muscle,  and 
lying  almost  unappropriated  in  the  adipose  matter  of  the 
part. 

Occasionally  a fasciculus  of  muscular  fibres  exists,  called, 
by  Albinus,  Transversus  Perinei  Alter,  which  arises  in  front 
of  the  former  muscle,  and  is  inserted  into  the  perineal  junc- 
tion just  behind  it. 

The  use  of  these  muscles  seems  to  be  to  contribute  to  fix 
the  bulb  of  the  urethra. 

The  Musculus  Sphincter  idni, 

Consists  in  a plane  of  fibres  which  surrounds  the  anus  in 
order  to  keep  it  closed.  It  has  two  fixed  points,  the  last 


MUSCLES  AND  EASClAl  OF  THE  PERINEUM. 


97 


bone  of  the  os  coccygis  behind,  and  the  perineal  union  of 
the  other  muscles  in  front;  its  lateral  diameter  occupies  about 
one-half  of  the  space  between  the  tuberosities  of  the  ischia, 
and  it  is  in  the  middle  of  this  space. 

Besides  closing  the  orifice  of  the  rectum  it  will  draw  the 
bulb  of  the  urethra  backsvards,  or  the  point  of  the  os  coc- 
c)''gis  forwards. 


The  Mmcuhis  Coccygeus, 

Belongs  to  the  interior  of  the  pelvis.  It  arises  by  a 
small,  tendinous,  and  fleshy  beginning,  from  the  spine  of 
the  ischium,  and,  lying  on  the  anterior  face  of  tlie  anterior 
sacro  sciatic  ligament,  it  is  inserted  into  the  side  of  the  last 
bone  of  the  sacrum  and  of  all  those  of  the  os  coccygis. 

It  draws  the  os  coccygis  forwards. 

A large  quantity  of  adipose  and  cellular  matter  exists  on 
the  side  of  the  rectum,  between  it  and  the  parietes  of  the 
pelvis,  concealing  the  perineal  surface  of  the  levatores  ani 
muscles. 

The  Musculus  Levator  Ani, 

Arises  fleshy  from  the  back  of  the  pubes  near  its  sym- 
physis, and  from  near  the  superior  margin  of  the  foramen 
thyroideum  above  the  obturator  internus  muscle.  It  also 
arises  from  the  aponeurosis  pelvica,  where  this  membrane  is 
extended  as  a thickened  semilunar  chord  from  the  superior 
margin  of  the  thyroid  foramen  towards  the  spinous  process 
of  the  os  ischium.  This  second  part  of  the  origin  of  the 
levator  ani  is  defectively  described  in  most  books  on  ana- 
tomy. It  is  then  seen  to  cross  obliquely,  as  far  as  the  spine 
of  the  ischium,  that  portion  of  the  obturator  internus  which 
arises  from  the  plane  of  the  ischium. 

From  this  extensive  origin  the  fibres  converge  and  descend 
backwards,  and  have  three  distinct  places  of  insertion;  the 
posterior  fibres  are  inserted  into  the  two  last  bones  of  the 
os  coccygis;  the  middle,  and  by  far  the  greater  number,  are 
inserted  into  the  semi-circumference  of  the  rectum  between 

Voi...  II. — 13 


9S 


ORGANS  OF  GENERATION. 


its  longitudinal  fibres  and  the  circular  fibres  of  the  sphincter 
ani;  and  finally,  the  most  anterior  fibres  pass  obliquely 
downwards  and  backwards  on  the  side  of  the  vesical  end  of 
the  membranous  part  of  the  urethra,  and  on  the  side  of  the 
prostate  gland,  and  are  inserted  into  the  common  place  of 
junction  of  the  perineal  muscles. 

The  Triangular  Ligament  of  the  Urethra, 

Is  a membrane  which  fills  up  the  space  below  the  sym* 
physis  of  the  pubes,  and  answers  as  a septum  between  the 
perineum  and  the  pelvis;  when  closely  examined,  it  is  seen 
to  connect  itself  to  the  internal  edges  pf  the  rami  of  the  pubes 
and  ischia  on  the  inner  posterior  sides  of  the  crura  penis  as 
far  down  as  the  beginning  of  the  latter.  At  its  lower  edge 
its  ligamentous  character  is  not  so  well  defined.  On  its  an- 
terior surface  is  the  bulb  of  the  urethra,  and  just  at  the  ex- 
tremity of  the  latter,  enclosed  by  the  ligament  and  adhering 
to  it,  are  Cooper’s  Glands.  A perforation  exists  in  it,  through 
which  passes  the  membranous  part  of  the  urethra.  This 
opening  is  not  very  apparent,  in  consequence  of  its  edges 
being  continued  a little  distance  on  the  canal,  but  by  detach- 
ing them  the  whole  becomes  well  defined. 

The  relative  situation  of  the  bulb  and  of  the  membranous 
part  of  the  urethra  is  such,  that  the  former  goes  towards  the 
anus,  while  the  latter  passes  upwards  towards  the  neck  of 
the  bladder,  they  consequently  form  a considerable  angle 
with  each  other.  The  membranous  part  of  the  urethra  is 
much  the  deepest,  the  recollection  of  which  is  all  important 
in  lithotomy,  as  it  teaches  us  to  avoid  the  one,  and  to  cut 
into  the  other.  It  may  also  be  observed,  that  the  hole  in 
the  triangular  ligament  is  an  inch  below  the  symphysis 
pubis. 

By  removing  the  upper  corner  of  the  triangular  ligament, 
we  are  made  acquainted  with  another  just  behind  it,  which 
is  totally  distinct.  This  ligament  is  half  an  inch  broad,  is 
thick  and  strong,  particularly  at  its  lower  edge,  and  is  very 
firmly  attached  laterally  to  each  pubes,  just  below  the  sym- 


PELVIC  FASCIA. 


99 


physis.  Mr.  Colles  calls  it  pubic  ligament,  with  great  pro- 
priety; I would  suggest  as  somewhat  more  expressive,  the 
term  Inter-Pubic  ligament,  as  it  serves  to  distinguish  it  from 
another  called  pubic,  which  is  above  the  pubes,  and  de- 
scribed in  the  account  of  the  recti  abdominis  muscles.  The 
breadth  of  this  having  been  stated  at  half  an  inch,  it  is  ob- 
vious that  the  hole  in  the  triangular  ligament,  is  half  an  inch 
below  its  lower  edge. 

Pelvic  Fascia. 

The  Pelvic  Fascia  [Aponeurosis  Pelvica)  connects  the 
bladder  to  the  sides  of  the  pelvis.  ‘‘This  fascia  descends  from 
the  ilio-pectineal  line  to  about  midway  in  the  depth  of  the 
pelvis;  here  it  is  reflected  from  the  surface  of  the  muscles 
[the  Levatores  Ani)  and  applies  itself  to  the  prostate  gland 
and  bladder  on  the  body  of  which  it  is  ultimately  lost.  At 
the  angle  of  its  reflection,  this  fascia  appears  particularly 
strong  and  white,  but  becomes  more  weak  and  thin  as  it 
lines  the  muscles  and  covers  the  bladder.  In  tracing  this 
membrane  it  will  be  seen  that  from  the  pubes  just  below  the 
symphysis,  a pointed  production  of  it  constituting  its  anterior 
margin  is  fixed  into  the  side  of  the  neck  of  the  bladder. 
This  pointed  production  on  each  side  is  called  by  most  ana- 
tomists the  anterior  Ligaments  of  the  bladder.  Between 
them,  just  beneath  the  symphysis  of  the  pubes,  a poucb  large 
enough  to  receive  the  end  of  the  finger,  is  formed  by  the 
union  of  the  fasciae  of  the  two  sides;  this  pouch  connects 
the  middle  anterior  part  of  the  neck  of  the  bladder  to  tlie 
lower  margin  of  the  symphysis  pubis.”* 

This  fascia  adheres  closely  to  the  periosteum  of  the  pubes, 
between  the  upper  margin  of  the  thyroid  foramen  and  the 
crista  of  the  pubes;  about  the  middle  third  of  the  linea  in- 
nominata  it  is  obviously  a continuous  membrane  with  the  iliac 
fascia  which  covers  the  iliacus  internus  muscles;  but  behind 
this,  again,  it  arises  from  the  remaining  third  of  the  linea 
innominata. 


Colles’  Surgical  Anatomy. 


100 


OKGANS  OP  GENERATION. 


The  portion  of  this  fascia  which  Mr.  Colies  speaks  of  as- 
particularly  strong  and  white,  forms  a bow,  the  concavity 
of  which  looks  upwards,  one  end  of  the  bow  being  fastened 
to  the  pubes  above  the  foramen  thyroideum,  and  the  other 
end  to  the  ischium  above  its  spine.  The  perineal  surface 
of  this  bow  is  an  important  point  of  the  origin  of  the  le- 
vator ani.  Above  the  bow  this  fascia  is  very  thin,  for 
the  fibres  of  the  obturator  internus  can  be  readily  seen 
through  it. 

At  the  bow  the  fascia  divides  into  two  laminae,  one  pur- 
suing hs  course  to  the  bladder  and  rectum;  the  other  covers 
the  lower  part  of  the  obturator  internus  muscle,  and  there- 
by constitutes  the  obturator  fascia.  The  levator  ani  is  in- 
terposed between  the  two  laminae.  The  aponeurosis  pelvi- 
ca  also  forms  a bow  or  semilunar  edge  in  front  of  the  sacral 
nerves. 


CHAPTER  II. 

OF  THE  ORGANS  OF  GENERATION  IN  THE  FEMALE. 

The  Copulative  Organs  in  the  female  are,  the  Vulva  and 
the  Vagina;  the  Generative  are  the  Uterus  and  the  Ovaria. 

SECT.  I. OP  THE  VULVA. 

The  term  Vulva  is  applied  to  the  most  superficial  of  the 
copulative  organs,  and  consists  in  the  Mons  Veneris,  the 
Labia  Externa,  the  Labia  Interna,  the  Clitoris,  the  Vesti- 
bulum,  the  Orificium  Urethrae,  the  Fourchette,  and  the  Fos- 
sa Navicularis. 

The  Mons  Veneris  is  the  protuberance  on  the  fore  paid; 
of  the  pubes.  Its  size  varies  considerably  according  to  the 


THE  VULVA. 


101 


state  of  obesity  of  the  subject,  in  consequence  of  its  being 
formed  by  a deposite  of  fat  between  the  skin  and  the  bone; 
in  corpulent  Avomen  it  is  very  large  and  prominent,  where- 
as in  such  as  are  much  emaciated  it  simply  describes  the 
outline  of  the  hones.  The  skin  there  is  abundantly  fur- 
nished with  sebaceous  glands  seated  in  the  cellular  texture 
beneath  it,  and  about  the  size  and  shape  of  millet  seed.  At 
the  age  of  puberty  a growth  of  hair  takes  place  upon  it, 
which  is  not  so  long  as  the  correspondent  growth  upon  men, 
and  is  not  so  much  disposed  to  spread  itself  over  the  loAver 
part  of  the  abdomen,  as  life  advances.  In  women  who 
have  abused  coition  these  hairs  become  much  curled. 

The  Labia  Externa  are  a continuation  of  the  mens  vene- 
ris downwards  in  the  form  of  an  oblong  eminence  on  either 
side.  Their  elevation  is  produced  in  the  same  way  by  a 
deposite  of  fat  beneath  the  skin.  They  are  somewhat 
broader  and  more  prominent  above  than  below.  On  the 
side  which  is  next  to  the  thigh  the  integument  is  common 
skin,  sparingly  covered  with  hair;  but  on  the  other  face  it 
is  a mucous  membrane,  being  a continuation  of  that  of  the 
vagina.  The  skin  here,  as  well  as  at  the  commencement  of 
every  mucous  membrane,  is  insensibly  changed  into  the 
latter.  They  have  many  sebaceous  glands  externally,  and 
mucous  glands  internally,  upon  them. 

Much  cellular  membrane,  like  that  of  the  scrotum,  is 
found  in  their  interior  structure,  whereby  they  enjoy  great 
extensibility  in  order  to  favour  the  dilatation  of  the  parts 
in  parturition.  The  rima  which  exists  between  them  is  the 
Fissura  Vulvse  of  authors,  and  is  about  twice  the  length  of 
the  orifice  of  the  vagina:  this  arrangement  of  it  gives  in- 
creased facility  to  the  expulsion  of  the  foetus. 

The  Fourchette  or  Frenulum  Vulvse,  is  situated  at  the 
posterior  commissure  of  the  labia  externa,  and  is  a thin, 
narrow  transverse  duplicature  of  skin,  which,  owing  to  its 
weakness,  is  most  frequently  ruptured  at  the  first  act  of 
parturition,  and  then  disappears. 


102 


ORGANS  OF  GENERATION. 


The  Clitoris  bears,  in  some  respects,  a resemblance  to 
the  penis  of  the  male,  but  is  by  no  means  so  large.  It  is 
situated  immediately  below  the  symphysis  pubis,  and  con- 
sists in  a cylindrical  body  of  three  or  four  lines  in  diameter, 
with  two  crura.  The  body  is  an  inch  long;  the  crura  are 
likewise  of  the  same  length,  and  arising  from  the  internal 
face  of  the  corresponding  crus  of  the  pubes,  unite  beneath 
the  symphysis  so  as  to  form  the  body.  The  body  is  not 
straight,  but  has  the  anterior  half  bent  downwards  and  for- 
wards. The  exterior  covering,  or  capsule  of  the  clitoris, 
in  its  texture,  resembles  the  elastic  ligamentous  membrane 
of  the  corpus  cavernosuni  penis;  and  is  moreover,  filled 
within  by  a similar  cavernous  or  cellular  structure,  which  is 
divided  into  two  equal  parts  by  a septum  pectiniforme,  and 
is  susceptible  of  distention  during  sexual  excitement.  The 
clitoris  is  supplied  also  with  blood  vessels  and  nerves  like 
the  penis,  and  is  held  up  to  the  under  part  of  the  symphy- 
sis pubis  by  a suspensory  ligament. 

The  anterior  extremity  of  the  body  of  the  clitoris  is 
found  in  the  rima  vulvie,  about  an  inch  below  the  upper 
commissure  of  the  labia  externa.  It  projects  some\vhat, 
and  bears  a general  resemblance  in  shape  with  the  end  of 
the  penis,  whence  its  name  of  glans  ditoridis;  but  it  has 
not  the  same  organization,  excepting  the  delicacy,  the  ex- 
treme sensibility,  and  the  vascularity  of  the  skin  which  co- 
vers it.  The  clitoris  has  no  corpus  spongiosum,  neither  is 
it  concerned,  like  the  penis,  in  conveying  the  urine  from 
the  bladder.  Its  glans  is  covered  by  a doubling  of  skin 
called  the  prepuce,  and  is  likewise  furnished  with  the  glan- 
dulae  Tysoni,  from  whidi  is  discharged  a smegma,  or  se- 
baceous fluid  as  in  the  male.  The  prepuce  does  not  furnish 
a regular  well  defined  fraenum. 

The  Erector  Clitoridis  muscle  corresponds  with  the  erec- 
tor penis.  It  arises  from  the  ascending  ramus  of  the  ischi- 
um, and,  covering  the  inferior  face  of  the  crus  clitoridis, 
runs  as  far  forwards  as  the  commencement  of  the  body. 

The  Labia  Interna  are  two  duplicatures  of  the  mucous 


THE  VULVA. 


103 


membrane  of  the  vulva,  which  pass  down,  one  on  each  side, 
from  the  clitoris.  The  prepuce  of  the  latter  terminates,  on 
either  side,  in  the  labia,  while  the  latter  are  continued  up- 
wards, by  a narrow  process,  to  the  under  surface  of  the 
glans  clitoris.  They  arise,  all  along  their  base,  from  the 
internal  sides  of  the  labia  externa,  or  majora;  and  being, 
wider  in  the  middle  than  elsewhere,  they  terminate  insen- 
sibly about  half  way  down  the  orifice  of  the  vagina.  Be- 
tween the  laminae  of  each  one  is  placed  a vascular  cellular 
substance,  susceptible  of  distention  and  of  partial  erection 
during  sexual  excitement.  In  young  subjects  their  vascu- 
larity communicates  a vermilion  tinge,  which  is  lost  and 
becomes  brownish  in  the  progress  of  life.  As  they  are  ef- 
faced during  parturition,  their  chief  use  seems  to  be  a pro- 
vision for  the  great  distention  of  the  vulva,  which  then  oc- 
curs. 

The  labia  interna  are  about  half  an  inch  broad  in  the  na- 
tural state,  and  do  not  project  obviously  beyond  the  labia 
externa,  except  in  cases  of  extreme  emaciation,  where  the 
prominence  of  the  latter  has  been  destroyed  by  a removal 
of  its  fat.  They  are,  however,  very  subject,  as  the  indivi- 
dual becomes  old,  to  a pointed  elongation,  increasing  their 
breadth  to  an  inch,  or  an  inch  and  a half;  and  to  become 
thickened  and  indurated.  A tribe  of  Hottentots,  the  Bos- 
chismans,  living  near  the  Cape  of  Good  Hope,  are  uniform- 
ly subject  to  this  enlargement;  which,  for  a long  time  was 
represented,  by  travellers,  as  an  organ  superadded  to  what 
is  common  in  the  human  species. 

The  Vestibulum  is  a depression  of  twelve  or  fifteen  lines 
long,  between  the  labia  interna;  it  is  bounded  above  by  the 
clitoris  and  below  by  the  orifice  of  the  vagina.  It  is  abun- 
dantly furnished  with  mucous  lacunje. 

The  Urethra  of  the  female  has  its  external  orifice  {Ori- 
ficium  Urethrae)  in  the  inferior  part  of  the  vestibulum, 
about  one  inch  below  the  glans  clitoridis,  and  is  generally 
marked  by  a slight  rising,  which  is  easily  distinguished  by 


104 


ORGANS  OP  (J.ENERATION. 


the  sensation  of  touch  alone;  its  margin  is  often  bounded  by 
a little  caruncle  on  each  side.  The  urethra  itself  is  an  inch 
long,  larger  and  much  more  dilatable  than  that  of  the  male; 
its  course  is  obliquely  downwards  and  forwards  from  the 
neck  of  the  bladder;  passing  under  the  symphysis  of  the 
pubes,  and  being  slightly  curved  from  that  cause.  It  con- 
sists of  two  membranes,  a lining  and  an  external  one.  The 
lining  membrane  is  a continuation  of  that  of  the  bladder; 
it  is  thrown  into  several  longitudinal  folds,  and  has  many 
mucous  follicles  in  it.  The  external  coat  of  the  urethra 
consists  of  condensed  laminated  cellular  membrane,  forming 
a cylindrical  body  of  half  an  inch  in  its  transverse  diameter, 
and  which  has  given  the  idea  of  the  existence  of  a prostate 
gland  in  the  female.  The  lower  and  lateral  surfaces  of  this 
cylinder  are  in  contact  with  the  vagina,  forming  a protube- 
rance into  its  cavity;  and  the  upper  surface  is  firmly  con- 
nected to  the  triangular  ligament  of  the  pubes. 

The  Fossa  Navicularis  is  that  portion  of  the  rima  vulvas 
which  is  below  the  vestibulum,  and  anterior  to  the  orifice 
of  the  vagina. 

SECT.  II. — OP  THE  VAGINA. 

The  Vagina  is  a thin  membranous  canal  which  leads  from 
the  vulva  to  the  uterus.  It  is  from  four  to  six  inches  in 
length,  differing  according  to  age  and  pregnancy,  and  being 
much  shorter  in  women  who  have  borne  children  than  in 
virgins.  It  is  placed  between  the  bladder  in  front  and  the 
rectum  behind,  being  flattened  by  them  so  as  to  bring  its 
anterior  and  posterior  surfaces  into  contact.  Its  anterior 
extremity  is  the  smallest  of  the  two,  and  presents  its  great- 
est diameter  vertically,  while  that  of  the  posterior  is  trans- 
verse. As  it  follows  accurately  the  central  line  of  the  pel- 
vis, it  is  consequently  curved  with  its  concavity  forwards. 
Its  anterior  parietes  are  shorter  than  the  posterior,  both  from 
the  smaller  depth  of  the  pelvis  in  this  direction,  and  from 
their  mode  of  connexion  with  the  uterus. 


THE  VAGINA. 


105 


The  vagina  is  formed  by  two  tunics;  a fibrous  and  a mu- 
cous one.  The  first  is  external,  of  a light  red  colour,  highly 
elastic,  and  seems  to  consist  of  condensed  cellular  membrane, 
the  fibres  of  which  are  much  intermixed,  and  pass  in  every 
direction.  It  is  vascular,  and  immediately  adjacent  to  the 
large  venous  sinuses  of  the  pelvis.  The  mucous  membrane 
being  a continuation  of  that  of  the  vulva,  is  at  and  near  its 
anterior  orifice  of  a vermilion  tinge;  while  posteriorly  it 
is  grayish  and  frequently  spotted,  so  as  to  give  it  a marbled 
appearance;  its  thickness  diminishes  as  it  recedes  from  the 
external  orifice;  and  upon  being  floated  in  water  many  mu- 
cous lacunae  are  observable  upon  it. 

The  internal  surface  of  the  vagina  is  commonly  covered 
with  the  mucus  which  comes  from  its  lacunae.  On  the  an- 
terior or  pubic  portion  it  is  diyided  longitudinally  by  a mid- 
dle ridge,  which  commences  by  a sort  of  tubercle  just  below 
the  orifice  of  the  urethra,  and  proceeds  backwards,  becoming 
indistinct  as  it  approaches  the  uterus.  Transverse  ridges 
formed  in  the  same  way  by  folds  of  the  mucous  membrane, 
arise  from  the  sides  of  the  last  at  its  anterior  poi’tion,  and 
give  a roughness  to  that  part  of  the  vagina.  The  inferior 
side,  or  that  next  to  the  rectum,  has  the  same  kind  of  ar- 
rangement of  the  mucous  membi’ane,  but  not  so  distinct.  In 
a majority  of  subjects  the  uterine  half  of  the  vagina  is  per- 
fectly smooth,  but  the  rule  does  not  always  hold. 

The  Corpus  Spongiosum  Vaginae  is  an  erectile  tissue  like 
that  of  the  penis,  and  closely  resembles  in  structure  the  cor- 
pus spongiosum  urethrae.  It  is  placed  at  the  anterior  end 
of  the  vagina,  on  its  outer  circumference,  just  below  the 
clitoris,  and  at  the  base  of  the  labia  minora  or  interna.  It 
is  an  inch  broad,  and  a line  or  tvyo  thick,  adheres  closely 
to  the  fibrous  coat  of  the  vagina,  and  extends  around  the  su- 
perior semi-circumference  of  the  orifice,  but  not  around  the 
inferior.  It  is  frequently  called  Plexus  Retiforrnis. 

The  Sphincter  Vagina  Muscle  surrounds  the  anterior  ori- 
Voj..  II, — 14 


106 


OKGA^:S  OF  GENEKATION. 


lice  of  the  vagina,  and  covers  the  plexus  retiformis.  It  is 
about  an  inch  and  a quarter  wide,  and  arising  from  the  body 
of  the  clitoris  passes  backwards  and  downwards  to  be  in- 
serted into  the  dense,  white  substance,  in  the  centre  of  the 
perineum,  common  to  these  muscles,  the  transversi  perinei 
and  the  anterior  point  of  the  sphincter  ani. 

The  Transversus  Perinei  of  the  female,  has  the  same  cir- 
cumstances of  origin  and  insertion  as  in  the  male,  but  is  not 
quite  so  strong. 

On  each  side  of  the  orifice  of  the  vagina,  near  its  middle, 
is  frequently  found  a mucous  gland  the  size  of  a garden  pea: 
it  corresponds  with  Couper’s  gland  of  the  male  subject. 

The  Hymen,*  one  of  the  attributes  of  the  virgin  state,  is 
placed  at  the  anterior  orifice  of  the  vagina  for  the  purpose 
of  closing  it,  and  commonly  remains  until  it  is  ruptured  by 
violence.  In  all  cases,  except  where  there  is  an  unnatural 
adhesion,  it  leaves  a small  orifice  for  the  passage  of  mucus 
and  of  menstrual  blood.  In  my  own  observations,  I have 
found  it  most  frequently  crescentic,  the  convexity  of  the 
crescent  presenting  downwards,  and  the  horns  upwards,  but 
in  some  cases  it  is  to  one  side.  Next  in  frequency  to  the 
lunated  is  the  circular  shape,  where  it  surrounds  complete- 
ly the  orifice  and  leaves  a hole  in  its  own  centre.  There 
are  some  other  varieties,  such  as  its  being  fleshy,  fasci- 
culated, unequally  divided  into  two  portions,  and  so  on, 
which  are  narrated  by  different  writers.  Being  simply  a 
duplicature  of  the  mucous  membrane,  it  is  generally  so  weak 
as  to  be  ruptured  at  the  first  act  of  copulation,  or  even  from 
slighter  causes  during  infancy;  but  occasionally  it  becomes 
thickened  and  so  strong  as  to  require  division  with  the  knife. 
After  the  rupture  of  the  hymen  its  place  is  indicated  in  sub- 
sequent life  by,  from  two  to  six  small  tubercles,  called  Ca- 
runculae  Myrtiformes,  which  are  its  remains. 

* J.  G.  Tolber.  Diss.  de  Variet  Hymen.  Haller,  Icon.  Anat.  Fasc.  i. 
Albin.  Acad.  Annot.  Lib.  iv.  Santorini,  Septemd.  I'ab. 


UTERtrS  AND  ITS  APPENDAGES. 


107 


The  peritoneum,  in  descending  from  the  uterus  anteriorly, 
touches  the  top  of  the  vagina  for  a little  distance,  and  is 
then  reflected  to  the  bladder,  but  posteriorly,  almost  the 
upper  half  of  the  vagina  has  a peritoneal  coat  before  this 
membrane  is  reflected  to  the  rectum.  The  attachment  of 
the  vagina  to  the  bladder  is  strong  and  close  just  about  the 
urethra,  but  its  connexion  with  the  rectum  is  by  rather 
loose  cellular  substance. 


SECT.  III. OF  THE  UTERUS  AND  ITS  APPENDAGES. 

The  Uterus,  or  womb,  is  a compressed  pyriform  body, 
the  larger  end  of  which  stands  upwards,  while  the  lower  is 
directed  downwards  and  is  attached  to  the  vagina.  Unim- 
pregnated, it  is  two  and  a half  inches  long,  and  one  and  a 
half  in  diameter  at  its  widest  part.  The  posterior  face  is 
very  convex,  while  the  anterior  is  almost  flat  or  very  slight- 
ly convex.  It  is  about  one  inch  in  thickness.  It  is  divided 
by  anatomists  into  fundus,  body,  and  neck.  The  fundus  is 
formed  by  its  superior  extremity,  and  comprises  the  space 
between  the  orifices  of  the  fallopian  tubes j the  neck  is  the 
lower  cylindrical  portion,  of  about  an  inch  in  length;  and 
the  body  is  the  part  intermediate  to  the  two.  On  the  ex- 
terior circumference  of  the  uterus  there  are  no  marks  or 
lines  distinguishing  these  several  portions  from  each  other. 

The  uterus,  being  destined  to  lodge  the  foetus,  from  a 
short  period  after  conception  to  the  moment  of  birth,  has  a 
cavity  ready  for  its  reception.  The  shape  of  this  cavity 
bears  some  general  but  not  a rigid  resemblance  to  that  of 
the  organ  itself,  and  is  so  much  flattened  as  to  have  its  an- 
terior and  posterior  parietes  in  contact  or  nearly  so.  The 
cavity  of  the  body  is  an  equilateral  triangle  of  eight  or  ten 
lines  in  diameter;  the  sides  of  the  triangle  are  bent  inwards 
in  parabolic  curves,  in  such  a way  as  to  present  their  con- 
vexities to  the  cavity  of  the  uterus:  this  of  course  occasions 
an  apparent  elongation  of  the  angles.  The  inferior  angle 


lOS 


OK(xANS  OF  GENERATION. 


is  continued  into  the  cavity  of  the  neck,  while  the  two  su- 
perior run  into  their  respective  fallopian  tubes.  From  this 
arrangement  it  happens  that  the  parietes  of  the  uterus  are 
only  two  or  three  lines  thick  on  the  angles  of  the  triangu- 
far  cavity,  while  at  the  middle  they  are  from  four  to  six 
lines.  The  cavity  of  the  neck  has  not  its  anterior  and  pos- 
terior sides  so  near  together  as  that  of  the  body,  and  is  ra- 
ther cylindrical,  being  smaller  however  at  the  upper  and 
lower  ends  than  in  the  middle.  This  arrangement  gives 
to  its  sides  a paraboloid  curvature  which  presents  its  con- 
vexity outwards,  differing  in  that  respect  from  the  corres- 
ponding curvature  in  the  cavity  of  the  body. 

The  cavity  of  the  neck  terminates  in  the  vagina  by  an 
orifice  about  the  size  of  a small  writing  quill,  but  ovoidal, 
and  presenting  its  long  diameter  transversely.  This  orifice 
is  the  Os  Tincse,  or  Orificium  Externum  Uteri,  frequently 
without  apparent  disease  I have  seen  it  conoidal,  with  its 
base,  half  an  inch  in  diameter,  presenting  downwards.  The 
upper  orifice,  whereby  the  cavity  of  the  neck  communicates 
with  that  of  the  body,  is  not  subject  to  such  fluctuations  in 
size;  it  is  occasionally  called  orificium  internum  uteri,  and 
is  generally  somewhat  larger  than  a small  writing  quill. 
The  os  tincae  is  bounded  before  and  behind  by  the  lips  of 
the  uterus,  formed  by  the  projection  of  the  neck  into  the 
vagina.  For  the  most  part  the  anterior  side  of  the  vagina 
is  directly  continuous  with  the  anterior  lip,  so  that  its  pro- 
jection is  very  inconsiderable,  and  indeed  not  appreciable 
to  the  finger;  at  the  same  time,  this  lip  is  rather  thicker 
than  the  posterior.  The  projection  of  the  latter,  on  the  con- 
trary, is  always  well  marked,  because  the  vagina  instead  of 
being  inserted  into  its  ridge  is  joined  to  the  posterior  sur- 
face of  its  base. 

The  cavity  of  the  uterus  is  lined  by  a very  thin  mucous 
membrane,  a continuation  of  that  of  the  vagina.  This  mem- 
brane is  of  a light  pink  colour,  which  changes  to  a vermilion 
during  the  period  of  menstruation;  it  is  furnished  with  vil- 
losities,  which,  though  seen  with  difficulty  in  the  usual  way, 
may  be  rendered  apparent,  by  floating  the  uterus  in  water; 


UTERUS  AND  ITS  APPENDAGES.  lOD 

V 

and  it  adheres  so  closely  to  the  substance  of  the  uterus,  that 
it  seems  to  form  an  inseparable  portion  of  it,  which  can 
neither  be  dissected  or  macerated  off  entirely,  as  in  the  case 
of  other  mucous  membranes. 

This  membrane  is  smoothly  laid  upon  the  cavity  of  the 
body,  and  gives  it  a polished  shining  surface.  On  the  ca- 
vity of  the  neck,  it  is  wrinkled  along  the  anterior  and  the 
posterior  parietes;  there  being  a longitudinal  line  running 
along  the  centre,  and  on  each  side  of  this  line  transverse  or 
oblique  elevations  or  duplicatures;  the  whole  presents  an 
arborescent  appearance,  technically  called  the  arbor  vitse. 
In  the  interstices  of  these  duplicatures  there  are  some  small 
mucous  glands  or  lacunse,  which  as  their  orifices  are  exposed 
to  obliteration  from  inflammation  or  some  other  irritation, 
they  become  distended  into  small  spherical  sacs  by  the  ac- 
cumulation of  their  habitual  secretion.  Naboth,  from  seeing 
them  in  this  state,  mistook  them  for  eggs,  or  the  rudiments 
of  the  foetus,  and  the  error  has  been  commemorated  by  their 
being  called  Ovula  Nabothi. 

The  uterus  is  covered  completely  by  the  peritoneum ; in 
the  reflection  of  the  latter  from  the  rectum  to  the  bladder, 
it  adheres  to  the  uterus  by  a subjacent  cellular  substance, 
which  allows  it  to  be  dissected  off  without  difficulty.  The 
same  duplicature  of  peritoneum  which  encloses  the  uterus, 
is  also  reflected  from  each  of  its  lateral  margins,  by  their 
whole  length,  to  the  corresponding  side  of  the  lesser  pelvis, 
and  forms  the  Lateral  or  the  Broad  Ligaments,  (Ligamenta 
Lateralia,  Lata. ) The  peritoneum,  in  passing  from  the  ute- 
rus forwards  to  the  bladder,  forms,  on  each  side,  a duplica- 
ture not  very  distinct,  and  depending  in  a measure,  upon 
the  state  of  the  bladder;  this  constitutes  the  Anterior  Liga- 
ments. The  same  membrane,  in  passing  from  the  back  of 
the  uterus  to  the  rectum,  and  in  covering  the  posterior  su- 
perior end  of  the  vagina,  also  forms,  on  each  side,  a dupli- 
cature denominated  the  Posterior  Ligaments;  they  are 
always  better  seen  than  the  anterior.  Muscular  fibres  are 
said  to  be  found  occasionally  between  the  laminae  of  these 


110 


ORGANS  OP  GENERATION. 


several  duplicatures,  running  in  the  direction  of  the  latter;* 
they  have  not  been  presented  to  me  in  such  a way  as  to  ar- 
rest my  attention. 

The  broad  ligaments,  along  with  the  uterus,  form  a trans- 
verse septum,  passing  from  one  side  of  the  pelvis  to  the 
other,  and  contain,  between  their  laminae,  the  arteries  and 
the  veins  which  belong  to  the  uterus  and  ovaries. 

Besides  the  duplicatures  of  peritoneum,  the  uterus  is  re- 
tained in  its  position  by  the  Ligamenta  Rotunda,  one  on 
each  side.  These  round  ligaments  arise  from  the  sides  of  the 
uterus,  a little  below  the  insertion  of  the  Fallopian  tubes, 
and  going  between  the  laminae  of  the  broad  ligament,  reach 
finally  the  internal  abdominal  ring;  they  then  traverse  the 
abdominal  canal  and  the  external  ring  after  the  manner  pre- 
cisely of  the  spermatic  chord,  and  terminate  by  several 
fasciculi  in  the  fatty  cellular  matter  of  the  mons  veneris 
and  of  the  labia  majora.  The  round  ligaments  are  rather 
smaller  in  the  middle  than  at  either  extremity;  they  consist 
of  a condensed  cellular  or  fibrous  structure,  and  have  many 
blood  vessels  in  them.  It  has  been  asserted!  that  they  con- 
tain strongly  marked  muscular  fibres,  some  of  which  come 
from  the  uterus,  and  others  from  the  broad  muscles  of  the 
abdomen.  No  evidence  of  this  fact  has  as  yet  been  pre- 
sented to  me,  though  I do  not  deny  it;  and,  indeed,  think 
it  probable,  that  such  fibres  may  be  developed  there  during 
gestation. 

The  texture  of  the  uterus  is  very  compact,  and  of  a carti- 
laginous feel;  it  is  composed  of  fibrous  matter  intermixed 
with  a great  many  blood  vessels.  In  regard  to  its  fibrous 
structure,  there  is  no  subject  in  anatomy  on  which  opinions 
are  more  divided;  or  more  authoritative,  and  numerous  on 
both  sides  of  the  question.  Some  deny  its  existence  at  any 
period,  while  others  admit  it  as  a constant  condition;  others, 
again,  limit  its  duration  only  to  the  period  of  pregnancy. 

* J.  F.  Meckel,  vol.  ii.  p.  605. 

f J.  F,  Meckel,  loc.  cit. 


UTERUS  AND  ITS  APPENDAGES. 


Ill 


Without  dwelling  on  the  value  of  the  several  doctrines,  and 
the  means  and  observations  tending  to  support  them;  it  may 
be  sufficient  here  to  mention  that  the  structure  of  the  uterus 
takes  on  very  important  and  strongly  marked  changes,  in 
passing  from  the  unimpregnated  state,  to  that  of  advanced 
gestation.  In  the  first  the  fibres  look  ligamentous  and  pass 
in  every  direction,  but  so  as  to  permit  the  uterus  to  be  lace- 
rated more  readily  from  the  circumference  to  the  centre  than 
in  any  other  course;  it,  indeed,  manifests  an  indisposition 
to  be  torn  in  a laminated  manner.  The  fibres,  moreover, 
break  off  short,  are  separated  by  the  blood  vessels,  and  seem 
to  contain,  in  their  interstices,  something  like  fibrine. 

In  the  impregnated  state,  on  the  contrary,  the  vessels 
become  immensely  increased  in  size,  the  laminated  struc- 
ture becomes  very  evident,  and  submits  readily  to  the  tear- 
ing of  one  layer  from  the  other;  these  laminae  consist  of 
fibres,  which  are  principally  parallel  with  each  other.  The 
muscular  nature  of  these  fibres  seems  to  be  sufficiently 
proved,  by  their  powerful  contraction  in  the  expulsion  of 
the  fcetus,  and  on  being  irritated  by  the  introduction  of  the 
hand.  They  are,  however,  not  red  like  other  muscles,  but 
of  a very  light  colour,  as  those  of  the  bladder  and  intestines; 
and  are  collected  into  fasciculi  of  peculiar  flatness  and  loose- 
ness. The  development  of  this  muscular  structure  is  not, 
however,  limited  to  the  pregnant  state,  but  is  disposed  to 
manifest  itself  on  all  occasions  which  produce  an  increased 
size  in  the  uterus.  This  fact  was  first  exemplified  to  me  in 
a small  scirrhus  of  a virgin  uterus,  presented  by  Dr.  Hugh 
L.  Hodge,  and  has  been  still  further  confirmed  in  a case, 
where  the  scirrhus  was  five  or  six  inches  in  diameter;  also, 
in  a virgin  uterus,  very  much  enlarged  from  scirrhus,  pre- 
sented by  Dr.  Charles  D.  Meigs.  A similar  fact  has  been 
noticed  by  Lobstein,  of  Strasbourg,  where  the  tumour  was 
also  steatomatous. 

The  fibres  of  the  uterus,  examined  near  the  term  of  preg- 
nancy, consists  in  two  planes  separated  by  the  large  blood 
vessels,  one  within  and  the  other  without.  These  layers 
are  I’eadily  divisible  into  subordinate  laminae,  intermixed 


112 


ORGANS  OF  GENERATION. 


with  one  another,  but  yet  to  a considerable  extent  sepa- 
rable. The  external  layer  is  thicker  than  the  internal,  and 
both  have  an  increased  thickness  at  the  fundus,  while  they 
are  much  diminished,  and  indeed  indistinct,  at  the  cervix. 

The  fibres  generally  are  either  circular  or  longitudinal, 
but  many  of  them  are  oblique.  The  exterior  surface  of  the 
external  plane,  is  composed  principally  of  longitudinal  fibres, 
within  which  are  the  circular.  The  inner  plane,  on  the  con- 
trary, has  the  circular  fibres  external,  and  the  longitudinal 
internal.  In  both  planes  the  circular  fibres  are  more  abun- 
dant at  the  fundus,  and  the  longitudinal  upon  the  body  of 
the  uterus;  but,  generally  speaking,  there  are  collectively 
more  longitudinal  than  circular  fibres. 


Of  the  Fallojnan  Tubes. 

The  Fallopian  Tubes  ( Tubse  Fallopianx)  are  two  mem- 
branous canals,  one  on  either  side,  fixed  in  the  superior 
margin  of  the  broad  ligaments  of  the  uterus.  They  serve 
to  conduct  the  rudiments  of  the  embryo,  from  the  ova- 
rium into  the  uterus.  They  are  about  four  inches  long, 
and  extend  from  the  upper  angle  of  the  uterine  cavity  to 
the  side  of  the  pelvis;  their  outer  extremity  is  loose,  and 
hangs  upon  the  posterior  face  of  the  broad  ligament  over  the 
ovarium,  consequently  inclines  downwards,  thereby  form- 
ing an  angle  with  the  other  portion. 

At  their  uterine  extremities  the  fallopian  tubes  are  about 
the  size  of  the  -vas  deferens,  resemble  it  strongly,  and 
scarcely  admit  a hog’s  bristle;  but  having  proceeded  about 
one  half  of  their  length,  they  begin  to  enlarge,  and  con- 
tinue to  do  so  rapidly  for  an  inch,  until  they  reach  the 
size  of  a writing  quill;  they  then  contract  again  somewhat, 
and  immediately  afterwards  expand  into  a broad  trumpet- 
shaped mouth.  The  latter  has  an  oblique  orifice,  the  edge 
of  which  is  extremely  irregular,  by  being  resolved  into  a 
number  of  ragged  fringe-like  processes,  of  unequal  size  and 
length;  and  which,  as  a whole,  are  called  Corpus  Fimbria- 


UTERUS  AND  ITS  APPENDAGES. 


113 


turn  or  Morsus  Diaboli.  One  of  the  longest  of  these  pro- 
cesses adheres  to  the  external  end  of  the  ovarium. 

The  fallopian  tube  is  covered  by  the  peritoneum,  and 
consists  of  two  coats : the  external  is  fibrous,  and  bears  suf- 
ficient resemblance  to  the  structure  of  the  uterus  to  be  con- 
sidered a continuation  of  it;  the  internal  is  mucous,  and  is 
likewise  a continuation  of  the  corresponding  one  of  the  ute- 
rus. The  external  end  of  the  tube,  which  is  called  Pavil- 
ion by  the  French  anatomists,  is  flaccid,  thin,  and  generally 
in  a collapsed  state,  as  -it  is  formed  solely  b}'  the  mucous 
membrane,  assisted  by  the  peritoneum,  neither  of  which  fur- 
nishes resistance  sufficient  to  keep  it  expanded;  but,  as  many 
blood  vessels  enter  into  its  composition,  their  turgescence, 
in  sexual  excitement,  probably  communicates  a certain  de- 
gi’ee  of  erection. 

Of  the  Ovaries. 

The  Ovaries,  \ Ovaria,  Testes  Muliebres,)  two  in  num- 
ber, one  on  either  side,  are  situated  on  the  posterior  face  of 
the  broad  ligaments,  by  a duplicature  of  which  they  are  sur- 
rounded, and  are  twelve  or  fifteen  lines  below  the  fallopian 
tubes.  Their  shape  is  that  of  a compressed  ovoid,  about 
half  the  size  of  the  male  testicle;  their  long  diameter  is  ho- 
rizontal; they  are  suspended  from  the  broad  ligament  rather 
by  the  edge  than  by  the  flat  surface,  so  that  they  project, 
and  are  to  a considerable  degree  pendulous.  Their  distance 
from  the  uterus  varies  from  an  inch  to  an  inch  and  a half, 
and  from  the  internal  end  of  each  one,  there  proceeds  a 
small  vascular  fibrous  chord,  the  Ligament  of  the  Ovarium, 
which  is  inserted  into  the  uterus,  somewhat  below  the  ori- 
gin of  the  fallopian  tube. 

From  their  being  the  seat  of  conception,  they  have,  in 
the  youthful  and  healthy  female,  a pliancy  and  succulency, 
indicative  of  their  state  of  preparation  for  the  act;  but  in 
advanced  life  they  diminish  much  in  volume  and  become 
hard  and  dry.  Their  surface,  originally  smooth  or  slightly 

Vo£.  IL— 15 


OKCtANS  OF  (SKNEaATION. 


1 14 

embossed;  is  subsequently  rendered  uneven,  by  repeated 
acts  of  conception  leaving  on  it,  a number  of  cicatrices  or 
small  stellated  fissures.  They  are  of  a light  pink  colour. 
Within  the  peritoneal  coat  is  another,  the  Tunica  Albugi- 
nea, of  a strong,  compact,  fibrous  texture,  like  the  same 
coat  of  the  testicle,  and  sending  inwards  many  processes. 

The  structure  of  the  ovarium  is  not  ascertained  with 
entire  satisfaction,  though  the  grosser  arrangement  of  it  is 
known.  But  few  females,  of  such  as  are  presented  in  our 
dissecting  rooms,  have  these  parts  in  a state  fit  for  study, 
owing  to  age,  disease,  or  intemperate  sexual  indulgence; 
my  best  opportunities  have  been  derived  from  post  mortem 
examinations  in  private,  of  individuals  of  from  fourteen  to 
twenty,  where  the  virgin  state  had  been  preserved.  When 
an  ovarium  of  the  latter  kind  can  be  got,  by  cutting  through 
the  tunica  albuginea  simply,  and  then  tearing  open  the 
organ,  it  will  be  found  to  consist  in  a spongy  tissue,  abun- 
dantly furnished  with  blood  vessels  from  the  spermatic  ar- 
tery and  vein.  In  this  spongy  tissue  are  from  fifteen  to 
twenty  spherical  vesicles  {Ovula  Graajiana)  varying  in 
size  from  half  a line  to  three  lines  in  diameter;  the  larger 
ones  are  nearer  the  surface,  and  from  having  caused  the  ab- 
sorption of  the  tunica  albuginea,  may  sometimes  be  seen 
through  the  peritoneal  coat,  and  give  to  the  surface  of  the 
ovarium  its  embossed  condition.  The  vesicles  contain  a 
transparent  fluid  supposed  to  be,  or  to  have  within  it,  the 
rudiments  of  the  embryo.  As  the  vesicles  are  evolved 
they  advance  from  the  centre  to  the  circumference.  Their 
parietes  are  thin,  transparent,  and  have  creeping  through 
them  minute  arterial  and  venous  ramifications. 

The  organs  of  generation  in  the  female  are  supplied  with 
blood  jmincipally  from  the  internal  pudic  and  other  branches 
of  the  hypogastric  artery;  their  veins  run  into  the  hypo- 
gastric. Their  nerves  come  from  the  sacral  and  from  the 
hypogastric  plexus. 


THE  LACTIFEROUS  GLAJTDS. 


115 


The  Bladder  and  the  Rectum,  with  unimportant  ex- 
ceptions are  the  same  in  both  sexes.  The  Levator  Ani,  the 
Coccygeus,  and  the  Sphincter  Ani,  are  also  similar.  The 
pelvic  aponeurosis  in  the  female,  besides  connecting  the 
bladder  to  the  sides  of  the  pelvis,  is  also  attached  to  the  an- 
terior part  of  the  vagina.  The  triangular  ligament  of  the 
urethra  also  exists,  but  under  circumstances  somewhat  mo- 
dified by  the  close  connexion  of  the  urethra  with  the  va- 
gina. ' 


CHAPTER  III. 

OF  THE  LACTIFEROUS  GLANDS  OR  BREASTS. 

The  Breasts  {JMammse)  of  the  female,  are  intended  for 
the  secretion  of  milk,  and  thereby  to  maintain  the  connex- 
ion between  mother  and  infant,  for  some  time  after  the  ute- 
rine life  of  the  latter  is  passed.  All  mammiferous  animals 
exercise  this  function;  in  birds  there  is  a sort  of  substitute 
for  it,  in  the  changes  which  take  place  In  the  first  stomach 
or  crop  during  incubation.  In  the  male  subject  there  is  also, 
a small  glandular  body  on  each  side,  which  has  the  same  or- 
ganization as  in  the  female,  but  is  in  miniature,  and  always 
remains  in  a collapsed  state,  with  some  rare  exceptions, 
when  it  has  been  known  to  expand  in  volume,  and  to  fur- 
nish a secretion,  as  in  the  female.* 

* In  a male  patient,  now  resident  in  the  Fliiladelpliia  Alms  House,  tlie 
phenomenon  of  a full  evolution  of  the  g^landular  structure  in  both  breasts  is 
manifested.  The  individual  (James  McIntyre)  is  forty -five  years  of,  age, 
the  breasts  are  as  large  as  those  of  a nursing  woman,  but  the  nipples  are 
not  proportionately  evolved.  Though  his  frame  is  robust,  and  well  set,  tlie 
voice  is  feminine;  his  external  organs  of  generation  are  about  the  size  of 
those  of  a boy  of  fourteen  or  fifteen.  Thinking  that  there  might  be  an  in- 
ternal state  approaching  to  hermaplu’odism,  he  informed  me,  on  inquii-ing, 
that  in  earlier  life  he  had  the  usual  inclinations  for  the  female.  He  also  in- 


116 


THE  EACTIPEKOUS  GLANDS. 


The  breasts  are  two  in  number,  one  on  either  side;  they* 
are  situated  on  the  same  level,  in  front  of  the  pectoralis 
major  muscle,  and  between  the  arm  pit  and  the  sternum. 
They  are  hemispherical,  and  have  their  base  united  to  the 
muscle  by  a thin  lamina  of  loose,  extensible,  cellular  sub- 
stance, containing,  even  in  corpulent  women,  but  little  fat. 
The  skin  which  covers  the  front  of  this  gland  is  very  fine  and 
thin,  so  that  the  blood  which  circulates  in  its  veins  may  be 
readily  seen.  Between  the  skin  and  the  front  surface  of 
the  gland,  there  is  a considerable  thickness  of  cellular  adi- 
pose matter,  which,  from  its  superabundance  in  certain  in- 
dividuals, gives  to  them  an  appearance  of  having  the  glands 
enormously  enlarged.  There  is,  however,  a great  variety 
in  the  size  of  the  glandular  structure  itself;  for  in  females 
■«  who  are  youthful  and  giving  suck,  they  are  much  larger 
than  in  such  as  have  passed  the  period  of  child-bearing,  and 
whose  health  is  impaired.  When  all  the  fatty  matter  has 
been  removed  from  a breast,  and  it  is  permitted  to  repose 
upon  a table,  its  hemispherical  shape  disappears,  and  it  then 
seems  rather  a flattened  circular  disk,  of  from  four  to  five 
inches  in  diameter. 

The  mamma  is  of  a very  light  pink  colour;  and  though 
very  flaccid  and  yielding  on  being  handled,  yet  its  texture 
is  actually  extremely  tough,  and  is  cut  only  by  much  force. 
With  the  exception  of  bone,  it  dulls  the  knife  sooner  than 
any  other  tissue  of  the  body.  Its  grosser  arrangement  con- 
sists in  lobes  of  different  sizes,  united  in  such  a way  by  cel- 
lular texture,  that,  though  they  can  be  pulled  somewhat 
apart,  they  cannot  be  entirely  separated  without  injury. 
These  lobes,  when  examined  through  the  skin,  give  to  the 
gland  a knotted  feel,  and  aire  sometimes  partially  affected 
by  Inflammation,  so  as  to  become  still  more  distinct.  The 
Lobes  are  composed  of  Lobuli,  which  are  resolvable  by  ma- 

formcd  me  that  this  unusual  development  took  place  seven  or  eig-ht  } ears 
ago,  owing  to  an  excessive  sahvation;  but  as  he  has  a reserve  on  the  sub- 
ject, this  statement  may  probably  be  received  with  some  qualifications.  I 
have  also  seen  a second  case,  in  which  the  voice  is  weak  and  feminine,  the 
generative  organs  have  not  been  examined,  duly,  1826. 


THE  LACTIEEKOrS  GLANDS. 


117 


ceration  and  particular  modes  of  treatment,  into  small  gra- 
niform  masses  {acini)  about  the  size  of  millet  seed,  and 
which  contain  the  ultimate  glandular  arrangement.  .The 
acini  themselves  consist  of  very  small  oblong  vesicles, 
united  by  cellular  substance,  and  by  the  common  blood  ves- 
sels; and  are  said  to  be  very  apparent  by  the  aid  of  a mi- 
croscope in  a lactescent  gland. 

The  excretory  ducts  {Ductus  Galactopliori,  Lactifcri) 
of  this  gland  are  numerous,  t They  are  of  an  arborescent 
shape,  and  begin  by  very  fine  extremities  or  ramuscles  in 
the  acini;  the  ramuscles  from  several  acini  coalesce  into  a 
larger  branch;  several  branches  unite  to  form  one  still 
larger,  and  so  on  successively  until  a lactiferous  duct,  con- 
stituting as  it  were  the  body  of  the  tree,  is  formed  by  this 
assemblage.  These  trunks  vary  considerably  in  size,  ac- 
cording to  the  number  of  tributary  branches,  and  having 
got  towards  the  centre  of  the  gland  near  the  nipple,  from 
two  to  four  of  them,  according  to  Cuboli,  run  into  a com- 
mon stock  or  root  called  a Lactiferous  Sinus.  These  si- 
nuses are  in  all  about  fifteen,  they  are  only  a few  lines  long, 
and  differ  in  size,  some  not  being  larger  than  a lactiferous 
duct,  while  others  have  a diameter  of  from  two  to  three 
lines.  The  sinus  at  the  end  next  to  the  nipple  terminates 
in  a sort  of  rounded  cul-de-sac;  but  from  the  extremity  of 
the  sac  a very  fine  conoidal  tube  arises  which  runs  through 
the  nipple,  and  conducts  the  milk  to  its  surface.  This  tube 
from  its  shape  is  suited  to  the  retention  of  milk;  in  addition 
to  which  it  is  sometimes  dilated  in  the  middle,  is  curved 
when  the  nipple  is  not  in  a state  of  erection  or  stretched 
out,  and  terminates  by  an  external  orifice,  which  is  so  fine 
as  to  be  seen  with  difficulty  by  the  naked  eye. 

The  excretory  ducts  of  the  breast,  under  which  term  may 
be  comprehended  the  lactiferous  ducts,  the  sinuses,  and  the 

* Marjolin,  Manual  D’Anat.  J.  F.  Meckel,  Manual  D’Anat, 

f Alex.  Kolpin,  Diss.  Inaug.  de  Stract.  Mam.  Cuboli,  Append,  ad  Sep- 
temd.  Tab,  Santorini.  Girardi,  Append,  ad  Septemd.  Tab.  Santorini. 


IIS 


THE  LACTIFEROUS  GLANDS. 


conoidal  tubes  in  the  nipple,  are  formed  by  a soft,  thin,  and 
semi-transparent  membrane,  very  capable  of  extension  and 
of  contraction.  The  trunks  generally  go  deeply  through 
the  substance  of  the  gland  and  are  tortuous,  but  do  not  anas- 
tomose laterally  with  one  another;  whence  it  happens  that 
the  lobes  and  lobules  of  the  gland  are  arranged  into  sec- 
tions, each  of  which  has  its  appropriated  excretory  duct. 
In  order  to  make  a complete  injection  of  the  gland,  each 
sinus  must  be  separately  injected  through  its  papillary 
conduit.  This  rule  is  not,  however,  of  universal  applica- 
tion, as  in  some  experiments  performed  by  the  elder  Mec- 
kel U]30n  women  advanced  in  pregnancy  and  during  lacta- 
tion, he  succeeded  in  forcing  mercury  through  one  sinus, 
by  its  ramitlcations,  into  those  of  another;  this  route  was 
supposed  to  have  been  through  the  finest  extremities  of  the 
ducts.  The  whole  gland  itself  may,  however,  from  the 
infrequency  of  this  circumstance,  and  from  the  difficulties 
and  partial  condition  of  these  anastomoses,  rather  be  consi- 
dered as  a congeries  of  smaller  glands,  kept  distinct  by  the 
interposition  of  eellular  substance  between  their  lobes;  but 
joined,  in  one  respect,  by  having  the  terminations  of  their 
excretory  tubes  collected  into  one  bunch  in  the  nipple. 
This  latter  circumstance  seems  to  be  only  a provision  for 
the  more  convenient  sucking  of  the  infant. 

The  excretory  ducts  are  no  where  furnished  with  valves, 
which  accounts  for  the  facility  with  which  they  may  be  in- 
jected backwards  from  the  nipple.  An  opinion  was  enter- 
tained by  Haller,  and  by  other  anatomists  after  him,  that 
some  of  these  ducts  originated  in  the  surrounding  cellular 
substance,  but  this  has  been  refuted  by  the  researches  of 
Cuboli.  Some  anatomists  have  thought  that  there  is  a di- 
rect communication  between  the  ends  of  the  lactiferous  tubes 
and  the  arteries,  veins,  and  lymphatics.  Mascagni,  after  a 
very  successful  injection  of  the  gland,  whereby  its  vesicles 
were  filled  with  quicksilver,  not  meeting  with  such  an  oc- 
currence, was  induced  to  think  that  when  the  communica- 
tion did  hajjpen,  it  was  produced  by  rupture. 


THE  PAPILLA. 


llJi 


The  Areola. 

In  virgins  is  a rose-coloured  circle,  which  surrounds  the 
base  of  the  papilla  or  nipple.  In  women  who  have  borne 
children,  or  in  those  whose  age  is  advanced,  it  becomes  of 
a dark  brown.  The  skin  of  the  areola  is  extremely  deli- 
cate, and  on  its  surface,  particularly  in  pregnant  or  nursing 
females,  there  are  from  four  to  ten  tubercles,  which  some- 
times form  a regular  circle  near  its  circumference,  and  in 
other  subjects  are  irregularly  distributed.  Each  of  these 
tubercles  has  near  its  summit  three  or  four  foramina,  which 
are  the  orifices  of  the  excretory  ducts  of  a little  gland  form- 
ing the  tubercle.  The  areola  consists  of  a spongy  tissue 
beneath  which  there  is  no  fat;  it  is  susceptible  of  distention 
during  lactation,  or  from  particular  excitement. 

The  greater  number  of  anatomists  have  considered  these 
tubercles  as  intended  only  for  the  secretion  of  an  unctuous 
fluid  which  lubricates  the  areola  and  nipple,  and  protects 
them  from  excoriation  by  the  sucking  of  the  infant.  It  is 
said,  however,*  that  when  some  time  has  elapsed  after 
a repast,  or  when  there  has  been  a long  interval  to  the 
nursing  of  the  child,  milk  flows  from  them  abundantly;  but 
that  in  inverse  circumstances  a transparent,  limpid  fluid  is 
distilled  in  small  drops;  all  of  which  would  tend  to  prove 
that  they  are  of  the  same  nature  with  the  mammjB  them- 
selves, being  only  smaller.  In  addition  to  them,  it  is  said, 
that  the  areola  and  the  nipple  are  furnished  with  a great 
number  of  sebaceous  glands,  which  do  not  elevate  themselves 
above  the  surface,  and  which  may  be  found  on  and  near  the 
tubercles. 

The  Papilla, 

Is  the  truncated  cone  in  the  centre  of  the  mamma,  of  the 
same  colour  with  the  areola  and  surrounded  by  it.  The 
lactiferous  tubes  terminate  on  its  extremity.  It  is  collapsed 


* J.  F.  Meckel, 


120 


THE  LACTIFEROUS  GLANDS. 


and  in  a very  pliable  state  for  the  most  part,  but  when  ex- 
cited it  swells,  becomes  more  prominent,  and  of  a deeper 
colour.  Its  skin  is  rough,  and  provided  with  numerous 
and  very  small  papillae.  Its  internal  structure  consists  of 
the  extremities  of  the  lactiferous  tubes  united  by  condensed 
cellular  membrane. 

The  mamma  is  supplied  with  blood  from  the  external 
thoracic,  intercostal,  and  internal  mammary  arteries.  Its 
veins  attend  their  respective  arteries.  The  nerves  come 
from  the  axillary  plexus  and  from  the  intercostals.  The 
lymphatics  run  into  the  internal  mammary,  intercostal,  and, 
axillary  trunks. 


BOOK  vn. 


Of  the  Organs  of  Respiration. 


The  Organs  of  Respiration  are  the  Larynx,  the  Trachea, 
and  the  Lungs. 


CHAPTER  I. 

OF  THE  LARYNX. 

The  Larynx  is  an  irregular  cartilaginous  tube,  that  forms 
the  upper  extremity  of  the  windpipe.  It  is  situated  imme- 
diately below  the  os  hyoides  and  the  root  of  the  tongue, 
where  it  may  be  felt  readily  through  the  integuments,  and 
by  its  prominence  contributes  to  the  outline  of  the  neck. 
Its  position  is  such,  that  it  is  bounded  behind,  by  the  pha- 
rynx, which  is  interposed  between  it  and  the  vertebrae  of 
the  neck;  and  laterally,  by  the  primitive  carotid  arteries  and 
the  internal  jugular  veins.  It  gives  passage  to  the  air  which 
is  inhaled  into  the  lungs  or  exhaled  from  them,  and  also 
contributes  essentially  to  the  production  of  the  voice.  Its 
special  use,  on  the  latter  occasion,  has  induced  some  anato- 
mists to  give  it  a description  apart  from  that  of  the  other 
organs  of  respiration;  but,  as  the  function  of  voice  is  subor- 
dinate to  that  of  respiration,  I have  preferred  an  observance 
of  its  most  natural  and  local  connexions. 

Five  distinct  cartilages  form  the  skeleton  of  this  structure; 
the  os  hyoides,  which  is  common  to  it  and  to  the  root  of  the 
VoL.  II. —16 


122 


ORGANS  OF  RESPIRATION. 


tongue,  also  contributes  to  its  superior  part,  in  a manner 
which  will  be  presently  mentioned.  The  cartilages  are 
one  Thyroid,  one  Cricoid,  one  Epiglottis  and  two  Aryte- 
noid. 

The  Thyroid  Cartilage  {Cartilago  Thyroidea)  is  the 
largest  of  the  five,  and  being  placed  about  one  inch  below  the 
os  hyoides,  produces  in  the  upper  part  of  the  neck  the  promi- 
nence called  Pomum  Adami.  It  consists  in  two  lateral  halves, 
which  in  most  individuals  are  perfectly  symmetrical,  and  are 
continuous  with  each  other  on  the  middle  line  of  the  body. 
These  two  sides  form  at  their  line  of  junction  an  angle  pro- 
jecting forwards,  and  resembling  that  of  the  canal  or  hydrau- 
lic gate:  the  superior  part  of  the  angle  is  more  prominent, 
than  the  inferior ; particularly  in  the  male  subject.  The 
sides  of  this  body  lean  outwards,  by  which  its  transverse 
diameter  above  is  increased. 

The  angle  is  terminated  above  by  a deep  notch,  from 
which  the  superior  margin  begins  to  form  a curvature,  on 
either  side,  like  the  letter  S;  the  inferior  margin  is  also 
somewhat  curved,  but  to  a smaller  degree.  The  posterior 
margin  of  each  half  is  nearly  straight,  but  is  elongated  above, 
with  the  aid  of  the  upper  margin,  into  a long  process,  the 
Cornu  Majus;  and  below,  with  the  aid  of  the  inferior  margin, 
into  another  process  not  so  long.  Cornu  Minus.  By  the 
latter  the  thyroid  cartilage  is  articulated  by  ligamentous 
fibres  called  the  lateral  crico-thyroid  ligament  to  the  side  of 
the  cricoid  cartilage,  which  thereby  becomes  the  fulcrum  of 
many  of  its  motions. 

The  internal  surface  of  each  half  of  the  thyroid  cartilage 
is  flat;  but  the  exterior  surface  is  slightly  marked  by  the 
sterno-thyroid  and  the  thyreo-hyoid  muscles. 

The  Cricoid  Cartilage  {Cartilago  Cricoidea)  is  placed  be- 
low the  thyroid,  and  is  the  base  of  the  larynx.  It  is  an  oval 
ring,  of  unequal  thickness  and  breadth. 

Its  inferior  margin  is  nearly  straight  and  horizontal,  and 
is  connected  to  the  first  ring  of  the  trachea;  it  is  also  thin- 
ner than  the  superior:  the  latter  is  very  oblique,  and  rises 


THE  LARYNX. 


123 


from  before  backwards  and  upwards  so  abruptly,  that  the 
breadth  of  the  cricoid  cartilage  behind  becomes  three  times 
as  great  as  it  is  in  front,  under  the  infei’ior  margin  of  the 
thyroid  cartilage.  The  superior  margin  has  on  each  side 
behind,  a little  head  or  convexity,  which  receives  the  base 
of  the  corresponding  arytenoid  cartilage,  and  forms  with  it 
a ball  and  socket  joint. 

The  interior  surface  of  the  cricoid  cartilage  is  smooth, 
and  covered  by  the  lining  membrane  of  the  larynx.  Its  ex- 
terior surface  is  flattened  on  each  side  behind,  by  the  poste- 
I'ior  crico-arytenoid  muscles;  it  is  marked  also  laterally  by 
other  muscles,  and  by  the  inferior  cornu  of  the  thyroid 
cartilage. 

The  cricoid  cartilage  is  embraced  by  the  inferior  margin 
of  the  thyroid,  but  in  such  a way  that  a triangular  interval 
is  left  in  front  between  the  two  cartilages. 

This  interval  is  filled  by  a ligament  adhering  to  its  mar- 
gins called  the  middle  Crico-Thyroid,  to  distinguish  it  from 
the  ligamentous  junction  between  the  inferior  cornua  of  the 
thyroid,  and  the  sides  of  the  cricoid.  The  middle  ligament 
has  some  small  apertures  in  it,  for  the  passage  of  blood  ves- 
sels and  of  nerves.  It  is  the  part  commonly  cut  in  the  ope- 
ration of  laryngotomy. 

The  Aiytenoid  Cartilages  {Cttrtilagines  Jlrytasnoidex) 
resemble  triangular  pyramids  curved  backwards,  and  about 
six  lines  long.  They  are  placed  on  the  upper  margin  of 
the  cricoid  cartilage  behind.  The  anterior  face  of  each  is 
uneven,  and  divided  into  two  concavities;  the  posterior 
face  forms  a single  cylindrical  concavity;  and  the  internal 
face,  by  which  it  approximates  its  fellow,  is  nearly  flat. 
When  joined  together,  the  two  cartilages  resemble  the  mouth 
or  spout  of  a pitcher,  from  whence  their  name.  Their  bases 
are  hollowed  into  a small  glenoid  cavity,  for  articulating 
with  the  cricoid  cartilage. 

A synovial  capsule  is  reflected  over  the  articulation,  be- 
tween the  arytenoid  and  the  cricoid  cartilage;  this  capsule 
is  strengthened  by  a few  scattered  ligamentous  fibres. 


ORGANS  OF  RESriRATIOX. 


1;^4 

The  Epiglottis  Cartilage  {Epiglottis)  is  situated  on  the 
posterior  face  of  the  base  of  the  os  hyoides,  being  enclosed 
partially  by  the  two  sides  of  the  thyroid  cartilage.  Its  ge- 
neral form  is  that  of  an  oval  disk;  the  upper  margin  of  it 
is  thin  and  rounded,  and  the  lower  part  is  elongated  into  a 
pedicle  which  adheres  to  the  entering  angle  of  the  thyroid 
cartilage. 

Its  surfaces,  though  nearly  flat,  are  not  fully  so;  for  an- 
teriorly, it  forms  a cylindrical  convexity,  and  posteriorly, 
a cylindrical  concavity,  from  side  to  side.  When  nicely 
stripped  of  its  covering,  a number  of  very  small  foramina 
are  seen  to  exist  in  it,  which  give  passage  principally  to  the 
ducts  of  muciparous  glands.  Its  connexions,  aided  by  its 
natural  elasticity,  keep  it  in  a vertical  attitude  behind  the 
base  of  the  tongue;  its  rounded  margin  is  elevated  above 
the  latter  and  overlooks  it. 

In  addition  to  the  preceding  cartilages,  there  are  always 
two,  and  sometimes  four  others.  On  the  top  of  each  ary- 
tenoid is  to  be  found  one,  (Corniculum  Laryngis;)  it  is  some- 
what triangular  and  elongated;  its  inferior  face  is  attached 
by  a few  ligamentous  fibres  to  the  end  of  the  arytenoid;  it 
is  included  in  the  soft  parts,  and  is  very  moveable.  The 
others,  when  they  exist,  are  found  on  the  margin  of  the 
glottis,  in  the  duplicature  of  the  membrane  which  is  ex- 
tended from  the  side  of  the  epiglottis  to  the  tip  of  the  ary- 
tenoid cartilage. 

From  the  whole  superior  margin  of  the  thyroid  cartilage 
included  between  its  greater  cornua,  there  proceeds  upwards 
a thin  lamina  of  somewhat  condensed  cellular  substance, 
which  is  attached  to  the  posterior  margin  of  the  base  and  of 
the  cornua  of  the  os  hyoides  their  whole  length.  . It  fills 
completely  the  space  between  the  os  hyoides  and  the  thyroid 
cartilage.  This  membrane  is  called  the  middle  Thyreo- 
hyoid  ligament,  though  its  ligamentous  character  is  by  no 
means  well  developed.  It  completes  the  periphery  of  the 
larynx  in  the  space  alluded  to,  and,  from  its  thin  yielding 


THE  EAKYNX. 


125 


nature,  presents  no  obstacle  to  the  motions  of  the  os  hyoides 
and  of  the  thyroid  cartilage  upon  each  other. 

The  posterior  margin  of  this  membrane,  on  each  side, 
is  bounded  by  a long,  rounded,  fibrous  chord,  the  Liga- 
mentum  Thyreo-Hyoideum  Laterale.  The  latter  is  extend- 
ed from  the  cornu  major  of  the  thyroid  cartilage  to  the  tu- 
berculated  extremity  of  the  os  hyoides,  and  frequently  con- 
tains, about  its  centre,  a small  oval  cartilage  or  bone,  (car- 
tilage triticea,)  not  quite  so  large  as  a grain  of  wheat. 

Immediately  under  the  body  of  the  os  hyoides,  between 
its  concave  face  and  the  middle  thyreo-hyoid  ligament,  is  a 
small  sac  formed  between  the  laminse  of  the  ligament,  and 
frequently  extending  itself  doAvnwards  as  far  as  the  notch 
of  the  thyroid  cartilage;  it  is  flat,  about  four  or  five  lines 
in  its  transverse  diameter,  and  presents  a shining  surface.  I 
have  never  seen  a fluid  in  it  in  the  natural  state;  its  secre- 
tion', however,  sometimes  becomes  excessive,  and  it  is  then 
elongated  downwards  over  the  front  of  the  thyroid  and  of 
the  cricoid  cartilage,  as  far  as  the  isthmus  of  the  thyroid 
gland.  In  this  state  it  frequently  forms  a small  fistulous 
opening,  at  its  lower  end,  through  the  skin,  which  is  marked 
by  a fold  of  the  latter  across  the  neck.  The  true  pathology 
of  the  disease  was  first  pointed  out  by  Dr.  Physick,  who 
cures  it,  in  some  cases>  by  the  introduction  of  lunar  caustic, 
and  in  others  by  extirpation. 

The  Thyreo-Arytenoid  Ligaments  are  two  in  number, 
on  each  side  of  the  larynx;  one  above  the  other  at  the  dis- 
tance of  three  lines.  The  inferior  is  extended  from  the  an- 
terior angle  of  the  base  of  the  arytenoid  cartilage,  to  the  in- 
ferior part  of  the  entering  angle  of  the  thyroid,  and  by  con- 
verging towards  its  fellow,  is  inserted  there  in  contact  with 
it.  Its  fibrous  structure  is  very  distinct.  It  also  bears  the 
name  of  Ligamentum  Vocale,  from  its  bordering  the  rima 
glottidis.  The  superior  thyreo-arytenoid  ligament  arises 
from  the  middle  of  the  anterior  edge  of  the  arytenoid  car- 
tilage, and  is  also  inserted  into  the  entering  angle  of  the 
thyroid;  it  is  more  distant  from  its  fellow  than  the  lower 
one,  and  goes  almost  parallel  with  it;  so  that  the  opening 


126 


ORGANS  OF  RESPIRATION. 


between  the  two,  is  both  larger  and  more  like  an  oblong. 
Its  fibrous  structure  is  less  distinct  than  that  of  the  lower. 
Both  the  upper  and  the  lower  ligaments  are  covered  by  a re- 
flection of  the  lining  membrane  of  the  larynx,  and  are  small 
round  fibrous  threads,  which  are  rendered  more  or  less  tense 
by  the  action  of  the  small  muscles  of  the  larynx. 

There  are  several  pairs  of  muscles  belonging  to  the  la- 
rynx. 

1.  The  Thyreo-Hyoideus,  as  observed  elsewhere,  looks 
like  a continuation  of  the  sterno-thyroideus.  It  arises  ob- 
liquely from  the  side  of  the  thyroid  cartilage  by  the  ridge 
there,  and  running  upwards  it  is  inserted  into  a part  of  the 
base,  and  into  nearly  all  the  cornu  of  the  os  hyoides. 

When  the  thyroid  cartilage  is  fixed,  it  draws  down  the 
os  hyoides;  but  when  the  latter  is  fixed,  it  draws  up  the 
thyroid  cartilage. 

2.  The  Crico-Thyroideus,  arises  tendinous  and  fleshy 
from  the  anterior  lateral  surface  of  the  cricoid  cartilage,  and 
passes  upwards  and  backwards  to  be  inserted  into  the  infe- 
rior cornu  of  the  thyroid  cartilage,  and  the  adjacent  part 
of  its  inferior  edge.  Use,  to  draw  these  cartilages  oblique- 
ly together. 

3.  The  Crico-Arytenoideus  Posticus,  arises  from  the  back 
of  the  cricoid  cartilage,  occupying  its  excavation,  and  is  in- 
serted into  the  posterior  part  of  the  base  of  the  arytenoid 
cartilage.  It  draws  the  arytenoid  backwards,  and  makes  the 
ligaments  tense. 

4.  The  Crico-Arytenoideus  Lateralis,  arises  from  the  side 
of  the  cricoid  cartilage,  and  is  inserted  into  the  side  of  the 
base  of  the  arytenoid.  Use,  to  draw  the  latter  outwards, 
and  open  the  chink  of  the  glottis. 

5.  The  Thyreo-Arytenoideus,  arises  from  the^posterior 
face  of  the  thyroid  cartilage  near  its  angle,  and  the  middle 


THE  LARYNX. 


127 


cvico-thyroid  ligament,  and  is  inserted  into  the  anterior 
edge  of  the  arytenoid  cartilage.  Use,  to  r^lax  the  ligaments 
of  the  glottis, 

6.  The  Arytenoideus  Obliquus,  arises  from  the  base  of 
one  arytenoid  cartilage,  and  is  inserted  into  the  tip  of  the 
other.  It  is  a very  small  fasciculus,  and  sometimes  only 
one  muscle  exists.  Use,  to  close  the  chink  of  the  glottis. 

7.  The  Arytenoideus  Transversus  is  always  a single 
muscle,  which  arises  posteriorly  from  the  whole  length  of 
one  arytenoid  cartilage,  excepting  a little  pai’t  of  the  tip, 
and  is  inserted,  in  a corresponding  manner,  into  the  other. 
It  fills  up  the  cylindrical  concavity  of  the  arytenoid  carti- 
lages. Use,  to  close  the  chink  of  the  glottis. 

8.  The  Thyreo-Epiglottideus,  consists  in  a few  fibres, 
and  arises  from  the  posterior  face  of  the  thyroid  cartilage 
near  its  entering  angle.  It  is  inserted  into  the  side  of  the 
epiglottis.  Use,  to  draw  the  epiglottis  downwards. 

9.  The  Aryteno-Epiglottideus  consists  also  in  a few  in- 
distinct fibres,  and  arises  from  the  superior  lateral  parts  of 
the  arytenoid  cartilage.  It  is  inserted  into  the  side  of  the 
epiglottis.  Use,  to  draw  the  epiglottis  downwards. 

These  two  last  muscles  are  generally  so  small  and  unde- 
fined, that  they  cannot  be  satisfactorily  distinguished  from 
the  adjacent  soft  parts.* 

On  the  posterior  face  of  the  thyroid  cartilage,  of  the  thy- 
reo-hyoid  membrane;  and  on  each  side  of  the  epiglottis 
cartilage,  surrounding  its  lower  paid,  with  the  exception  of 
its  posterior  face,  there  is  an  accumulation  of  cellular  and 
adipose  substance.  In  the  lower  part  of  this  substance  there 

* A muscle  of  a trian^lar  shape  has  lately  been  observed  the  En- 
glish anatomists,  situated  in  front  of  the  epiglottis,  passing  to  it  from  the 
base  of  the  os  hyoides;  it  is  called  flyo-Epiglottideus.  The  observations 
on  its  existence  have  not  yet  been  repeated  sufficiently  often  to  determine 
whether  it  belongs  to  the  normal  structure  of  the  body  or  not;  and  in  my 
own  dissections,  for  the  purpose  of  ascertaining  its  existence,  it  has  not  oc- 
cuired.  Am.  Med.  •Toiu’.  vol.  v. 


128 


ORGANS  OF  RESPIRATION. 


are  several  small  glandular  bodies,  sometimes  insulated  and 
sometimes  collected  together,  which  detach  their  prolonga- 
tions into  the  foramina  of  the  epiglottis  cartilage,  and  seem 
to  open  thereby  on  its  laryngeal  surface;  they  are  mucous 
glands. 

The  Arytenoid  Gland,  which  is  also  muciparous,  is  si- 
tuated in  front  of  the  arytenoid  cartilage,  in  the  duplicature 
of  the  mucous  membrane  which  passes  from  the  side  of  the 
epiglottis  cartilage  to  the  arj^tenoid;  It  is  a small  body  of 
a grayish  colour,  resembling  the  letter  L,  and  consists  in 
distinct  grains;  it  is  supposed  to  have  its  excretory  ducts 
opening  into  the  larynx.  It  is  frequently  wanting. 

The  interior  face  of  the  Larynx  is  lined  by  a mucous  mem- 
brane continuous  above  with  that  of  the  mouth  and  pharynx, 
and  below  with  that  of  the  trachea.  Where  it  is  reflected 
from  the  base  of  the  tongue  to  the  epiglottis  cartilage,  it 
forms  as  described,  a well  marked  vertical  fold  or  fraenum 
in  front  of  the  middle  of  the  latter,  and  on  each  side  of  this 
middle  fold  there  is  another,  not  so  distinct,  but  varying 
in  different  subjects.  The  three  folds  form  two  pouches  in 
front  of  the  epiglottis,  in  which  foo(|  is  sometimes  lodged. 
The  mucous  membrane  also  forms  the  duplicature  on  each 
side  already  alluded  to,  which  passes  from  the  lateral  part 
of  the  epiglottis  cartilage  to  the  arytenoid  of  the  same  side 
of  the  body.  This  duplicature  forms  the  superior  bounda- 
ry of  the  cavity  of  the  larynx,  and  is  very  soft  and  exten- 
sible, permitting  freely  the  epiglottis  to  be  depressed  and 
to  rise  again  into  its  vertical  position.  The  duplications 
of  the  two  sides,  taken  together,  form  an  oblong  oval  open- 
ing into  the  larynx,  passing  very  obliquely  upwards  and 
forwards  to  the  epiglottis,  and  terminated  behind  by  a notch 
between  the  cornicula  laryngis.  At  the  latter  place  the  mu- 
cous membrane  is  wrinkled  and  loose,  so  as  to  permit,  by 
its  extensibility,  free  motion  to  the  arytenoid  cartilages. 

After  adopting  the  preceding  arrangement,  the  lining 
membrane  of  the  larynx  passes  downwards;  it  covers 
smoothly  the  posterior  face  of  the  epiglottis,  adhering 


THE  LARYNX. 


129 


closely  to  it;  but,  when  it  reaches  the  thyreo-arytenoid  li- 
gaments, it  is  tucked  in  between  the  upper  and  the  lower 
one,  so  as  to  form,  on  either  side,  an  oblong  pouch,  the 
bottom  of  which  is  broader  than  its  orifice  between  the  li- 
gaments. This  pouch  is  the  ventricle  of  Galen,  or  of  Mor- 
gagni, or  of  the  larynx;  it  projects  into  the  fatty  glandular 
matter  on  the  posterior  face  of  the  thyroid  cartilage,  and 
has  its  base  resting  on  the  thyreo-arytenoid  muscle.  The 
continuation  of  the  membrane  afterwards  lines  smoothly  the 
cricoid  cartilage,  and  abounds  there  in  mucous  follicles. 

That  portion  of  the  larynx  which  is  formed  by  the  thy- 
reo-ajytenoid  ligaments,  and  the  pouches  between  them,  is 
the  structure  essential  to  the  formation  of  voice.  The  open- 
ing between  the  two  lower  ligaments  is  the  Rima  Glottidis, 
and  the  space  between  the  upper  ligaments  and  the  duplica- 
ture  of  the  mucous  membrane  passing  from  the  arytenoids 
to  the  epiglottis  cartilage,  may  be  termed  the  Glottis. 

The  Epiglottis  cartilage  is  principally  useful  in  prevent- 
ing articles  of  food  from  falling  into  the  glottis,  either  in 
swallowing  or  in  vomiting.  The  strength  of  its  muscles, 
however,  does  not  seem  to  be  sufficient  to  draw  it  down  over 
the  glottis,  as  many  physiologists  suppose;  on  the  contraiy, 
I am  induced  to  believe  that  the  glottis  is  rather  drawn  up- 
wards to  it.  If,  on  any  occasion,  it  be  depressed  or  bent 
down  over  the  glottis,  the  position  must  be  caused  by  me- 
chanical pressure  from  the  bulk  of  the  article  swallowed. 
But  the  latter  explanation  is  not  sufficient  to  account  for  the 
swallowing  of  fluids,  or  of  a very  small  body,  as  a pill  or 
a crumb  of  bread. 

Impressed  with  these  objections,  and’  unsatisfied  with  the 
common  theory,  I had  an  opportunity,  in  a dissection  a few 
years  ago,  of  witnessing  a position  of  these  parts  which  af- 
forded a satisfactory  explanation.  The  subject  was  a robust, 
muscular  man,  who  had  died  suddenly.  The  upper  orifice 
of  the  glottis  was  closed  and  protected,  but  by  an  arrange- 
ment precisely  the  reverse  of  the  received  opinion;  for  the 
epiglottis,  retaining  its  naturally  erect  position,  with  a 
..  Vox.  II.— 17 


130 


ORGANS  OF  RESPIRATION. 


slight  inclination  backwards,  had  the  opening  of  the  glottis 
drawn  up  so  as  to  come  in  contact  with  its  posterior  face. 
The  cricoid  cartilage,  it  has  been  mentioned,  slopes  on  its 
superior  margin  upwards  and  backwards;  the  front  surfaces 
of  the  arytenoid  cartilages,  in  their  natural  position,  are 
nearly  on  a line  with  this  slope,  or  a continuation  of  it;  the 
whole  may  therefore  be  considered  in  the  light  of  an  oblique 
plane,  rising  up  behind  the  epiglottis  cartilage.  By  a very 
slight  additional  elevation  of  this  plane  along  with  the  rota- 
tory motion  of  the  thyroid  cartilage  upon  its  lesser  cornua, 
the  plane  is  caused  to  come  in  contact  with  the  posterior 
face  of  the  epiglottis,  and  thereby  to  close  the  upper  open- 
ing of  the  glottis. 

The  principal  agents  in  this  motion  are  the  thyreo-hyoid 
muscles,  the  contraction  of  which,  causing  the  larynx  to 
ascend,  the  opening  of  the  glottis  is  brought  up  behind  the 
epiglottis,  and  thereby  secured  from  the  introduction  of 
food  into  it.  Whether  the  food  be  passed  from  the  mouth 
into  the  stomach,  as  in  swallowing,  or  from  the  stomach 
into  the  mouth,  as  in  vomiting,  is  equally  unimportant;  and 
the  security  is  the  same,  whether  the  article  be  small  or 
large,  fluid  or  solid.  Several  years  ago  I dissected  a gen- 
tleman, who  had  symptoms  of  sore  throat  with  swelling  of 
the  neck,  superadded  to  those  of  pulmonary  consumption; 
during  the  existence  of  his  sore  throat,  in  addition  to  the 
usual  difficulty  of  swallowing,  he  was  frequently  affected 
in  the  act,  with  strangulation  to  an  alarming  and  distressing 
degree.  In  the  dissection  it  was  found  that  an-abscess,  of 
considerable  extent,  existed  between  the  os  hyoides  and 
the  thyroid  cartilage,  and  involved  the  thyreo-hyoid  mus- 
cles. Without  knowing  at  the  time  the  value  of  this  ob- 
servation, I am  now  persuaded  that  the  strangulation  arose 
from  the  inactivity  of  the  thyreo-hyoid  muscles.  In  some 
ulcerations  of  the  epiglottis  cartilage  which  I have  had  an 
opportunity  of  seeing,  the  upper  circular  portion,  which 
projects  above  the  root  of  the  tongue,  has  been  lost;  if  the 
accident  be  confined  to  that  extent  only,  deglutition  is  not 
much  impaired,  because  still  enough  of  the  epiglottis  is  left 
to  perform  the  office  assigned  to  it,  as  the  upper  part  is  less 


TRACHEA. 


131 


essential.  The  cases  of  its  reputed  loss  by  wounds,  must 
be  considered  as  applying  themselves  to  this  upper  portion 
only,  because  a wound  low  enough  to  remove  the  whole 
body,  would  cause  such  a destruction  of  the  rima  glottidis, 
as  to  produce  an  embari’assment  of  respiration,  incompati- 
ble with  life. 

It  is  probable  that  the  inferior  constrictors  of  the  pha- 
rynx, as  well  as  the  stylo-pharyngeal  muscles,  assist  in  this 
use  of  the  thyreo  hyoidei. 

There  is  a well  marked  difference  in  the  larynx  of  the 
two  sexes.  In  the  female  it  is  generally  smaller  by  one- 
third  than  it  is  in  the  male;  the  thyroid  cartilage  is  also  less 
prominent,  in  consequence  of  its  two  halves  uniting  at  an 
angle  more  obtuse,  the  pomum  adami  is  therefore  seldom 
conspicuous.  The  rima  glottidis  is  also  smaller  in  women. 

The  nerves  of  the  larynx  come  principally  from  the  su- 
perior and  the  inferior  laryngeal  branches  of  the  par  vagum. 


CHAPTER  II. 

OF  THE  TRACHEA  AND  THE  GLANDS  BORDERING  UPON  IT. 

SECT  I. TRACHEA. 

The  Trachea,  or  Aspera  Arteria,  is  a cylindrical  canal  of 
four  or  five  inches  in  length  and  about  nine  lines  in  dia- 
meter, communicating  with  the  lungs  for  the  transmission 
of  air.  It  opens  into  the  larynx  above,  by  being  attached 
to  the  inferior  margin  of  the  cricoid  cartilage,  and  termi- 
nates in  the  thorax,  opposite  the  third  dorsal  vertebra,  by 
two  ramifications  called  Bronchiae.  In  this  course  it  is  si- 
tuated over  the  middle  line  of  the  neck,  beneath  the  sterno- 
thyroid muscles,  and  separated  from  them  by  the  deep- 
seated  fascia  of  the  neck  and  the  adipose  matter  beneath  it. 
It  is  placed  in  front  of  the  oesophagus,  between  the  primi- 


132 


ORGANS  OP  RESPIRATION. 


live  carotid  arteries  and  the  internal  jugular  veins.  When 
it  has  got  into  the  thorax,  it  inclines  slightly  to  the  right 
side  as  it  passes  behind  the  curvature  of  the  aorta.  Of  its 
two  branches,  the  right  bronchia  is  larger  than  the  other;  it 
is  also  less  slanting,  and  an  inch  long  before  it  divides;  it 
sinks  below  the  right  pulmonary  artery,  to  penetrate  the 
lung  about  the  fourth  dorsal  vertebra.  The  left  bronchia 
being  an  inch  longer,  sinks  into  the  lung  of  the  left  side, 
below  the  corresponding  pulmonary  artery  and  opposite  the 
fifth  dorsal  vertebra.  The  bronchiae  then  divide  and  sub- 
divide very  minutely  tbrough  the  lungs. 

Very  dissimilar  structures  enter  into  the  composition  of 
the  trachea;  they  are  cartilage,  ligamentous  fibre,  muscle 
and  a mucous  membrane. 

The  Cartilage  preserves  the  cylindrical  shape  of  the  tra- 
chea, and  consists  in  from  sixteen  to  twenty  distinct  rings, 
which  are  deficient  in  the  posterior  third  of  their  circumfe- 
rence. Each  ring  is  about  two  lines  broad,  and  half  a line 
thick,  and  is  kept  apart  from  the  one  above  and  below  it  by 
a small  interstice;  sometimes,  however,  they  run  into  each 
other. 

There  is  an  almost  uniform  similitude  betiveen  these  rings; 
the  principal  departure  from  which  is  observed  in  the  first 
being  rather  broadei  in  front  than  the  others,  and  in  the  last 
ring,  which,  by  its  corset-like  shape  in  front,  contributes  to 
the  beginning  of  each  bronchia. 

The  rings  of  the  bronchiae  are,  like  those  of  the  trachea, 
deficient  in  their  posterior  third,  and  the  same  arrangement 
holds  during  their  primitive  ramifications  in  the  lungs.  But, 
as  they  subdivide  more  and  more,  the  cartilages  do  not  suc- 
ceed each  other  so  closely,  are  smaller  segments  of  circles, 
and  are  not  regularly  deficient  at  the  posterior  third.  In 
place  of  the  latter,  the  whole  periphery  of  the  bronchial  ra- 
mification is  cartilage,  but  the  latter  consists  in  several  pieces 
put  end  to  end.  The  pieces  become,  after  a while,  more  and 
more  scattered  and  smaller,  till  they  finally  disappear. 

The  Ligamentous  Structure  of  the  trachea  and  of  the  bron- 


TRACHEA. 


133 


chise  is  very  evident  between  the  proximate  margins  of  the 
cartilaginous  rings,  and  fills  up  the  intervals  between  them 
so  as  to  make  the  tube  perfect.  This  tissue  may  be  traced 
over  the  surfaces  of  the  rings,  forming  their  perichondrium, 
so  that  they  may  be  considered  as  imbedded  in  it.  It  does 
not  exist,  satisfactorily,  in  the  human  subject,  in  the  interval 
behind,  where  a third  of  the  ring  is  defective,  but  in  the  bul- 
lock it  is  there  also.  In  the  smaller  ramifications  of  the 
hronchiae,  where  a complete  circle  is  formed  by  the  juxta-po~ 
sition  of  the  several  little  cartilaginous  segments,  it  is  proba- 
ble that  this  tissue  contributes  to  the  whole  periphery  of  the 
ramification. 

It  possesses  great  elasticity,  which  is  manifested  by  the 
rapid  shortening  of  the  trachea,  when  its  two  extremities  are 
stretched  apart  and  then  suddenly  let  loose.  And  it  is  the 
continuance  of  this  quality  of  elasticity,  in  the  minute  ra- 
mifications of  the  bronchise,  which  proves  the  existence 
of  this  tissue  there,  even  when  it  cannot  be  very  distinctly 
seen. 

The  Muscular  Structure  of  the  trachea  exists  at  the  carti- 
laginous deficiency  in  its  posterior  third,  and  consists  in  a 
thin  muscular  plane  whose  fibres  pass  transversely  between 
the  interrupted  extremities  of  the  cartilaginous  rings  of  the 
trachea  and  of  the  bronchise.  Thqse  transverse  fibres  begin 
at  the  first  ring,  and  exist  all  the  way  down  to  the  lungs; 
they  ai’ise  from  the  internal  faces  of  the  rings,  and  the  in- 
termediate elastic  ligamentous  tissue;  about  a line  beyond 
their  extremities.  Anteriorly,  they  are  covered  by  the  lining 
membrane  of  the  trachea,  and  posteriorly  by  cellular  tissue. 

In  the  lungs,  where  the  cartilages  become  scattered  and 
irregular,  the  muscular  fibres  are  said,  by  J.  F.  Meckel,  and 
by  M.  Reisseissen,*  to  perform  the  whole  circuit  of  the 

* De  Fabrica  Pulmonis.  Berlin,  1822.  M.  Laennec  says  (Traite,  dc 
1’ Auscultation,  Paris,  1826,  vol.  2.  p.  189,)  that  he  has  sought  in  vain  to 
venfy  these  observations  of  Keisseissen,  but  that  the  manifest  existence  of 
circular  fibres  upon  branches  of  a middling  size  and  the  - phenomena  of 
many  kinds  of  asthma,  induce  him  to  view  as  a thing  well  established, 
the  temporary  occlusion  of  the  small  bronchial  ramifications,  by  a spaS’ 
modic  contraction  of  their  parietes. 


134 


OKGANS  OF  KESPIRATION. 


bronchial  ramification,  and  to  be  visible  even  beyond  the 
existence  of  the  cartilaginous  pieces.  Soemmering  expresses 
a doubt  of  this  arrangement.'*  It  is  very  difficult,  in  such 
minute  structure,  to  arrive  at  a satisfactory  conclusion.  Lon- 
gitudinal fibres  are  also  said  by  Portal  to  exist  between 
the  contiguous  margins  of  the  cartilaginous  rings,  but  the 
fact  is  far  from  being  well  ascertained.! 

The  use  of  this  muscular  tissue  has  been  pointed  out,  for 
the  last  seven  or  eight  years  by  Di’.  Physick,  as  follows; 
In  expectoration,  it  diminishes  the  calibre  of  the  air  tubes, 
so  that  the  air  having  to  pass  out  with  increased  rapidity 
through  them,  its  momentum  will  bring  up  the  inspissated 
fluid  which  may  be  in  its  way.  This  very  ingenious  theory 
has  subsequently  been  advanced  by  M.  Cruveilhier,  of  Paris, 
possibly  without  a knowledge  of  his  having  been  anticipa- 
ted; but  certainly  not  without  the  claims  of  the  eminent  in- 
dividual to  whom  we  owe  it,  having  been  established  by  its 
publication.! 

The  Mucous  Membi’ane  of  the  trachea  lines  its  whole  in- 
terior periphery,  from  the  larynx  to  the  bronchiag,  and  is 
continued,  under  the  same  circumstances,  through  the  latter 
to  their  minute  divisions.  It  adheres  very  closely  to  the 
contiguous  structure,  and  is  continued,  in  the  substance  of 
the  lungs,  beyond  the  traces  of  any  of  the  other  tissues 
which  compose  the  trachea;  it  indeed  terminates  in  the  air 
cells.  It  is  thin,  reddish,  and  presents  an  abundance  of 
slightly  elevated  longitudinal  folds;  one  of  the  latter,  con- 
spicuous for  its  greater  size,  exists  at  the  commencement  of 
the  left  bronchia  and  is  yet  more  developed  in  the  still- 
born infant. 

The  exterior  circumference  of  the  mucous  membrane  is 
studded  with  muciparous  glands,  about  the  size  of  millet  seed. 

* Ext'imae  uutem  vel  posticae  ejus  fibrs  per  longitudinem,  a cartllag'ine  cri- 
coidea  ad  pulmcnes  usque  descendunt,  ac  vel  in  ipsis  trachex  ramis  baud  pa- 
rum  conspicui  sunt. — De  Corp.  Hum.  Fabrica. 

I Portal.  Anat.  Med. 

± Wistar’s  Anatomy,  3d  edition,  vol.  ii.  p.  64.  Phil.  1821. 


THE  THYROID  GLAND. 


135 


These  glands  are  particularly  conspicuous  and  abundant  on 
the  posterior  part  of  the  trachea  and  of  the  bronchise,  where 
the  deficiency  of  the  cartilaginous  rings  is  supplied  by  the 
membranous  structure  only;  and  more  of  them  exist  at  the 
lower  part  of  the  trachea  and  upon  the  roots  of  the  bronchise 
than  elsewhere.  They  are  placed  behind  the  muscular  layer, 
which  their  excretory  ducts  have  to  penetrate.  Besides  oc- 
cupying these  situations,  they  are  found  m the  interstices 
between  the  cartilaginous  rings,  but  here  they  are  much 
smaller.  The  raucous  membrane  abounds  so  much  in  the 
orifices  made  by  their  excretory  ducts,  that  it  looks  cribri- 
form, which  appearance  is  increased  by  floating  it  in  water. 

About  the  origins  of  the  bronchiac,  there  is  a considerable 
number  of  black  coloured  lymphatic  glands,  called  Bron- 
chial, which  it  is  easy  to  distinguish  from  the  preceding 
by  their  colour  and  much  greater  size. 

There  are  two  more  glands  of  a different  character,  which, 
though  they  do  not  enter  into  the  composition  of  the  tra- 
chea, yet,  from  their  locality,  are  most  conveniently  studied 
at  this  time:  they  are  the  Thyroid  and  the  Thymus. 


SECT.  II. OF  THE  THYROID  GLAND. 

The  Thyroid  Gland  ( Glandula  Thyroidea)  is  placed  on 
the  first  and  second  rings  of  the  trachea,  and  on  the  sides  of 
the  larynx. 

It  consists  in  a middle  portion,  which  is  thin,  of  variable 
magnitude  in  diflerent  individuals,  sometimes  entirely  want- 
ing, and  which,  being  stretched  across  the  upper  part  of  the 
trachea  just  below  the  larynx,  is  called  its  isthmus;  and  of 
two  lobes,  one  on  each  side,  which,  being  flattened  and 
ovoidal,  are  extended  upwards  on  the  side  of  the  larynx, 
and  downwards  on  the  side  of  the  trachea  and  of  the  oeso- 
phagus. Frequently  from  the  superior  part  of  the  isthmus, 
and  most  commonly  on  its  left  side,  a small  pyramidal  pro- 
cess runs  upwards  in  front  of  the  cricoid  and  of  the  thyroid 
cartilage,  and  is  attached,  by  ligamentous  fibres  to  the  os 


13(3 


ORGANS  OF  RESPIRATION. 


liyoides;  this  process,  however,  varies  much  in  its  size  and 
length  j I have  never  seen  it  double.  According  to  Mor- 
gagni and  Bleckel,  its  existence  is  much  more  common  than 
its  absence,  which  corresponds  with  my  own  observations. 
The  thyroid  gland,  when  extended,  measures  about  three 
inches  from  side  to  side. 

It  is  covered  in  front  by  the  sterno-hyoid  and  thyroid 
muscles,  and  laterally  by  the  omo-hyoid  and  the  sterno 
mastoid.  Embracing  the  trachea  and  the  sides  of  the  la- 
rynx, its  lobes  repose  upon  the  primitive  carotids,  and  the 
internal  jugular  veins. 

The  thyroid  gland  has  a capsule  which  is  not  very  easily 
raised  up,  but  serves  to  give  it  a polish;  it  is  also  invested 
by  the  condensed  cellular  membrane  of  the  part  called  fas- 
cia profunda.  Its  surface  is  smooth  and  uniform.  It  is  of  a 
dark  brown  colour.  When  cut  into  or  torn,  it  is  seen  to 
consist  of  several  lobules  adhering  to  each  other:  but  this 
arrangement  is  not  veiy  distinfct  except  in  an  enlarged  or 
diseased  state;  and  may  be  traced  most  easily  by  following 
the  course  of  the  large  blood  vessels,  which  pass  in  the  in- 
terstices between  the  lobules.  The  latter  contain  many 
small  vesicles,  or  cells,  filled  with  a transparent  or  yellow- 
ish and  somewhat  unctuous  fluid;  the  cells  are  frequently  in 
a collapsed  state,  which  prevents  them  from  being  manifest 
to  the  naked  eye. 

There  are  four  considerable  arteries  which  supply  this 
body,  two  on  each  side,  one  coming  from  the  external  ca- 
rotid and  the  other  from  the  subclavian.  The  veins  fol- 
low the  course  of  the  arteries  for  the  most  part.  Bichat 
has  made  a very  interesting  remark  on  the  subject  of  its 
blood  vessels;  that,  notwithstanding  their  size  and  number, 
and  minute  ramifications  in  it,  much  less  blood  remains  in 
its  capillary  system  than  in  that  of  the  liver  or  kidney,  as 
is  proved  by  the  quantity  of  water  it  tinges  in  maceration; 
he  therefore  infers  that  the  capillary  system  is  less  abun- 
dant. 

Anatomists  have  sought  in  vain  for  one  or  more  excre- 
tory ducts  to  this  body,  and  some  have  imagined  that  they 
had  found  them  terminating  in  the  trachea,  or  in  the  larynx. 


THE  THrROID.  GLAND. 


137 


Santorini  considered  the  pyramidal  process  from  the  isth- 
mus as  the  desired  duct.  The  emphysema  with  which  the 
gland  has  sometimes  been  affected  was  supposed  to  be  a 
proof  of  its  communicating  with  the  trachea  by  excretory 
tubes;  but  it  is  more  probable  that  the  air  was  forced  into 
the  cellular  substance,  uniting  its  lobules,  and  not  into  the 
structure  itself  of  the  gland.  The  settled  opinion  . now  seems 
to  be,  that  whatever  fluid  it,secretes  is  conveyed  away  by 
the  lymphatic  vessels.  Meckel  has  suggested,  that  as  this 
gland  is  more  voluminous  proportionately  in  early  infancy, 
particularly  its  pyramidal  process,  possibly  the  duct  may 
be  obliterated  when  the  gland  begins  to  be  restrained  in  its 
growth;  but  if  this  were  the  case,  the  duct  ought  to  have 
been  found  during  the  period  indicated.  The  probability 
is,  that  it  is  a diverticulum  of  blood  from  the  salivary  glands 
during  the  intermittence  of  their  action ; and  from  the  marked 
sympathy  between  it  and  the  brain  in  goitre,  it  may  exercise 
a corresponding  function  on  this  organ  during  its  intervals 
of  repose. 

Duverney*  has  described  a small  azygous  muscle  on  the 
middle  line  of  the  body,  coming  from  the  under  margin  of 
the  base  of  the  os  hyoides,  and  running  over  the  middle  of 
the  thyroid  cartilage,  to  be  inserted  into  the  upper  margin 
of  the  isthmus  of  the  thyroid  gland.  Soemmering  calls  it  Le- 
vator Glandulse  Thyroidese,  and  speaks  of  it  as  being  found 
more  frequently  on  the  left  side,  and  about  half  of  the 
breadth  of  the  thyreo  hyoideus.  After  many  special  exami- 
nations for  it,  I have  found  it  in  but  very  few  instances,  I 
thei’efore  consider  it  rare;  though  without  a close  attention 
to  structure,  the  pyramidal  process  of  the  isthmus  of  the 
gland  may,  from  the  similitude  of  colour  and  position,  be 
very  readily  mistaken  for  it,  which  I have  reason  to  believe 
is  frequently  the  case.t  Some  few  fibres  are  often  found 

* Essai  D’Anatomie  en  tableaux  imprimes,  pi.  IV.  Paris,  1745. 

^ The  unassisted  eye,  in  a strong  light,  is  generally  sufficient  to  deter- 
inhie  the  structure;  but  in  case  of  doubt,  by  boiling  the  gland,  if  there  be 
muscular  fibres  along  this  process,  theh  longitudinal  and  parallel  direction 
will  become  evident:  they  also  may  then  be  torn  asunder,  so  as  to  be  made 
still  more  distinct;  whereas  the  vesicular  structure  of  the  gland  is  not  sus- 
ceptible of  division  into  fibres. 


OK&ANS  01?  RESPIRATION’. 


J3S 

going  to  the  isthmus  of  the  gland  from  the  crico-thyroid, 
and  the  thyreo-hyoid  muscles,  or  from  the  thyroid  carti- 
lage. 

SECT.  III. OP  THE  THYMUS  GLAND.* 

This  body  (Gians  Thymus)  is  placed  between  the  tra- 
chea and  the  upper  extremity  of  the  sternum.  It  is  irre- 
gularly triangular,  its  broadest  part  being  above,  and  the 
narrower  below.  In  the  adult  it  is  in  a collapsed  and  shri- 
velled state,  and  scarcely  presents  a vestige  of  what  it  once 
was;  it  is,  therefore,  only  in  the  infant  that  it  can  be  satis- 
factorily studied. 

At  birth  it  is  much  larger,  not  relatively,  but  actually, 
than  it  is  in  the  adult,  and  extends  from  the  body  of  the 
heart  up  to  the  thyroid  gland.  It  is  of  a very  soft  consist- 
ence and  of  a pink  colour.  It  is  surrounded  by  a capsule 
of  cellular  substance,  which,  when  removed,  permits  the 
gland  to  be  resolved  into  two  lobes,  one  on  either  side, 
which  adhere  to  each  other.  These  lobes  may  be  separated 
with  facility  into  lobules,  and  contain  a whitish  fluid. 

It  is  visible  in  the  third  month  of  gestation,  and  conti- 
nues to  grow  till  the  end  of  the  second  year  of  extra-uterine 
life.  It  then  collapses,  and  its  structure  is  effaced  about  the 
twelfth  year;  its  remains  are  scarcely  distinguishable  sub- 
sequently from  the  surrounding  cellular  substance.  No  ex- 
cretory duct  has  been  found  for  it,  and,  though  it  clearly  be- 
longs to  foetal  and  infantile  existence,  its  use  is  problematical. 
The  probability  is,  that  it  is  a diverticulum  of  blood  from 
the  lungs  during  their  state  of  quiescence  in  foetal  life,  and 
until  their  structure  becomes  confirmed  and  proportionately 
evolved. 


CHAPTER  III. 

OF  THE  LUNGS. 

The  Lungs  (Pulmones)  are  the  essential  seat  of  the  pro- 
cess of  respiration,  and  occupy  the  greater  part  of  the  ca- 


THE  ETTNGS. 


139 


vity  of  the  thorax,  as  formed  by  the  ribs  and  the  intercos- 
tal muscles  on  the  sides,  by  the  sternum  and  its  cartilages 
in  front,  by  the  dorsal  vertebrae  behind,  and  by  the  dia- 
phragm below.  They  are  two  bodies,  placed  one  on  either 
side  of  the  thorax,  and  separated  from  each  other  by  the  heart 
and  its  great  vessels.  As  the  heart  is  the  only  organ  of 
much  volume  which  is  also  included  in  the  cavity  of  the 
thorax;  the  size  of  the  lungs  is  in  a direct  relation  with  the 
capacity  of  the  latter,  and  may  therefore  be  known  by  the 
external  indications  in  the  living  body.  It  is  probable  that 
there  is  no  void,  or  only  a very  small  one,  between  the 
sides  of  the  lungs  and  the  sides  of  the  thorax. 

Each  lung  forms  an  irregular  cone,  the  apex  of  which  is 
above,  and  the  base  below;  the  latter,  from  resting  upon 
the  diaphragm,  is,  consequently,  oblique  from  before  back- 
wards and  downwards,  and  is  also  concave.  The  surface 
which  reposes  against  the  periphery  of  the  side  of  the  tho- 
rax is  uniformly  rounded,  but  that  which  looks  towards 
its  fellow,  is  concave,  from  being  pressed  in  by  the  heart. 
From  the  oblique  direction  of  the  diaphragm,  the  vertical 
diameter  of  the  lung  behind,  when  it  is  fully  distended, 
goes  from  the  first  to  the  last  rib,  and  is  consequently  much 
more  considerable  than  the  vertical  diameter  in  front,  which 
extends  only  from  the  first  rib  to  the  inferior  end  of  the 
second  bone  of  the  sternum,  or,  in  other  words,  to  a level 
with  the  tendinous  centre  of  the  diaphragm. 

The  left  lung  is  divided  into  two  lobes  by  a deep  fissure, 
which  begins  behind,  on  a level  with  the  fourth  dorsal  ver- 
tebra, and  runs  obliquely  downwards  and  forwards  to  the 
anterior  margin  of  its  base.  A deep  fissure  in  a nearly  si- 
milar situation  is  observed  on  the  right  lung;  but  from  it 
another  fissure  branches  out  forwards,  by  which  the  right 
lung  is  divided  into  three  lobes.  The  internal  face  of  the 
left  lung  it  also  rather  more  concave  than  that  of  the  right, 
from  the  apex  of  the  heart  projecting  into  it.  The  right 
iung  is  more  voluminous  than  the  left,  which  corresponds 
with  the  greater  size  of  the  bronchia  on  this  side,  but  its 
vertical  diameter  is  not  so  great,  from  the  pressure  of  the 
liver  from  below. 


110 


ORGANS  OF  RESPIRATION. 


Near  the  middle  of  the  internal  face  of  each  lung  are  to 
be  seen  the  points  of  connexion  with  the  bronchia,  and  with 
the  pulmonary  vessels.  Before  these  the  anterior  margin 
is  thin,  and  more  or  less  winding  where  the  lung  is  intro- 
duced between  the  heart  and  the  front  parietes  of  the  tho- 
rax. When  the  lungs  are  fully  inflated,  but  a very  small 
portion  of  the  pericardium  can  be  seen  here  between  them. 
The  posterior  margin  is  thick,  and  rounded  where  it  rests 
against  the  vertebral  column. 

The  whole  rounded  cii’cumference  of  the  lung  as  well  as 
its  base,  though  they  are  in  contact  with  the  parietes  of  the 
thorax,  do  not  adhere  at  any  point  to  them.  The  connexion 
of  the  lung  by  which  it  is  maintained  in  its  situation,  is  en- 
tirely on  the  side  of  its  concave  face,  where  the  pulmonary 
vessels  and  bronchia  enter,  and  though  other  attachments 
are  frequently  found  springing  from  different  points  of  the 
thorax,  they  are  purely  the  results  of  disease. 

Of  the  Texture  of  the  Lungs. 

Each  lobe  of  the  lungs  is  divided  into  a great  many  dis- 
tinct lobules,  which  adhere  together  by  intermediate  cellu- 
lar tissue.  The  marks  of  these  divisions  are  apparent  on 
the  surface  by  lines  running  in  different  directions,  but 
they  are  made  still  more  distinct  by  tearing  them  asunder, 
This  connecting  cellular  substance  may  be  inflated  through- 
out by  a blowpipe  introduced  at  any  point  of  it.  These  lo- 
bules are  again  subdivided  into  very  fine  air  cells,  which 
may  be  considered  as  the  terminations  of  the  ultimate 
branches  of  the  bronchia.  The  cells  do  not  communicate 
laterally  with  one  another,  as  the  cells  of  the  bones,  but 
only  with  the  ramifications  of  the  bronchia,  to  which  they 
respectively  belong. 

Besides  the  ramifications  of  the  bronchiae,  the  substance 
of  the  lungs  is  composed  of  numerous  blood  vessels  and 
lymphatics,  and  is  well  supplied  with  nerves. 

The  blood  vessels  are  of  two  kinds,  the  pulmonary  and 
the  bronchial.  The  pulmonary  artery,  coming  from  the 
right  ventricle  of  the  heart,  divides  under  the  arch  of  the 


THE  LUNGS. 


Ml 


aorta  into  two  large  branches:  one  for  the  right  lung,  and 
the  other  for  the  left.  The  right  branch  is  larger  than  the 
left.  Each  of  these  branches  having  reached  the  upper 
part  of  the  root  of  its  respective  lung,  begins  there  to  dis- 
tribute itself  in  large  trunks,  which  divide  and  subdivide 
throughout  the  substance  of  the  lung.  The  terminating 
branches  finally  become  capillary,  and  ramify  in  the  pari- 
etes  of  the  fine  cells,  where  the  blood  which  they  carry,  from 
being  dark-coloured  and  venous,  is  so  altered  as  to  have  the 
arterial  qualities  restored  to  it,  and  to  become  of  a bright 
red.  From  the  ultimate  bi’anches  of  the  pulmonary  artery, 
arise  the  first  branches  of  the  pulmonary  veins.  These  are 
successively  accumulated  into  two  large  trunks  on  each 
side,  which,  issuing  at  the  lower  part  of  the  root  of  the  lung, 
go  to  open  into  the  left  auricle  of  the  heart.  It  has  been 
remarked  by  Mr.  Boyer  that  the  two  pulmonary  veins  are 
Jess  capacious  than  the  pulmonary  artery  of  the  same  side, 
in  which  they  manifest  a peculiarity,  differing  from  what 
exists  in  other  parts  of  the  body.  The  pulmonary  artery 
and  veins  are  distributed  in  company  with  the  bronchia. 
From  the  observations  of  Professor  Mayer,  it  appears  that 
valves  exist  in  the  pulmonary  veins,  contrary  to  the  gene- 
ral opinion  of  anatomists.  They  are  found  where  smaller 
trunks  join  the  larger  ones,  at  an  acute  angle,  but  there  are 
none  when  they  join  at  a right  angle.* 

The  second  order  of  blood  vessels,  being  the  bronchial, 
also  consists  in  arteries  and  in  veins,  and  belongs  to  the  nou- 
rishment of  the  lungs.  They  too  attend  the  branching  of 
the  bronchia.  The  arteries  pervade  the  substance  of  the 
lung  by  innumerable  fine  branches,  and  anastomose  with 
the  pulmonary  arteries.  The  bronchial  veins  also  anasto- 
mose with  the  pulmonary  veins,  but  finally  come  out  in 
small  trunks  from  the  root  of  the  lung,  and  empty  into  the 
vena  azygos. 

The  Lymphatics  of  the  lungs  are  numerous;  after  tra- 
versing the  black  bronchial  glands,  those  of  the  left  side 
empty  into  the  thoracic  duct,  and  those  of  the  right  into  the 


* Am.  Med.  Jour.  vol.  iii.  page  186. 


142 


ORGANS  OF  RESPIRATION. 


large  lymphatic  trunk  coming  from  the  right  upper  extre- 
mity. 

The  Nerves  come  principally  from  the  par  vagum.  Some 
of  them  are  distributed  along  with  the  bronchia,  and  may 
be  traced  to  the  mucous  membrane;  others  seem  to  be  more 
specifically  appropriated  to  the  vessels. 

It  will  now  be  understood  that  the  root  of  each  luno-  is 

O 

formed  by  the  pulmonary  artery,  the  two  pulmonary  veins, 
and  the  bronchia,  covered  by  the  pleura  where  the  latter 
extends  from  the  lung  to  the  pericardium.  The  relative  si- 
tuation is  such  that  the  pulmonary  artery  is  above,  the  bron- 
chia in  the  centre  and  behind,  and  the  pulmonary  veins 
below. 

The  lung  of  the  adult  is  of  a light  pink  colour,  with 
specks  or  patches  of  black;  in  early  life  there  is  much  less  of 
the  latter,  and  in  advanced  life  it  becomes  more  abundant. 

The  texture  of  the  lung  is  so  light  and  spongy  after  an 
animal  has  once  breathed,  that  its  weight  is  very  inconside- 
rable when  compared  with  its  volume.  Its  cells  are  left 
much  distended,  even  when  the  animal  is  dead,  and  not- 
withstanding, from  its  unusual  elasticity,  it  expels  a great 
quantity  of  air  when  the  thorax  is  opened,  and  is  thereby 
reduced  to  a third  ofats  size  during  life,  yet  it  retains 
enough  air  to  make  it  float  in  water,  or  even  in  spirits  of 
wine.  The  quantity  of  air  which  the  lungs  contain  difiers 
very  considerably  in  different  individuals,  depending  en- 
tirely on  the  capaciousness  of  the  thorax.  Its  medium 
amount  is  computed  at  one  hundred  and  forty-five  cubic 
inches;  thirty  cubic  inches  of  which  are  changed  at  every 
act  of  respiration. 

Of  the  Pleurse. 

Each  lung  has  its  covering  of  pleura.  This  membrane 
is  reflected  from  the  internal  surface  of  the  lung  to  the  ad- 
jacent side  of  the  pericardium,  and  is  then  spread  over  the 
interior  periphery  of  that  half  of  the  thorax  to  which  it  be- 
longs, lining  the  ribs  and  intercostal  muscles,  and  covering 
the  convex  face  of  the  diaphragm.  There  are,  therefore, 
two  pleurse,  each  of  which,  is  confined  to  its  appropriate 


THE  LUNGS. 


143 


half  of  the  thorax,  lining  its  cavity  and  covering  its  lung. 
The  Pleura,  like  other  serous  membranes,  is  a thin  membra- 
nous sac.  Its  circumference  is  entire,  like  that  of  an  inflated 
bladder,  there  is  therefore  no  point  or  line  at  which  one  may 
preferably  begin  an  account  of  its  course  and  attachments. 
To  commence,  however,  at  the  sternum;  the  pleura  goes 
thence  outwardly  to  line  the  lateral  parietes  of  the  thorax, 
as  formed  by  the  cartilages  of  the  ribs,  the  ribs  themselves, 
and  the  intercostal  muscles.  In  this  way  it  may  be  traced 
around  to  the  dorsal  vertebrae,  and  over  the  convex  surface 
of  the  diaphragm.  In  proceeding  along  the  first  rib,  which 
is  very  oblique,  it  forms  a sort  of  bulging  bag,  which  pro- 
jects towards  the  trachea,  lines  the  lower  part  of  the  scale- 
nus anticus  muscle,  and  receives  the  upper  extremity  of  the 
lung.  The  pleura  having  reached  the  dorsal  vertebrae, 
passes  from  their  sides  forwards,  to  the  posterior  part  of  the 
pericardium,  a very  small  portion  of  which  it  covers.  It 
then  goes  upon  the  posterior  face  of  the  pulmonary  vessels 
and  of  the  bronchia  to  the  lung;  and  applies  itself  closely  to 
the  latter.  It  then  covers  the  part  of  the  lung  posterior  to 
the  pulmonary  vessels,  and  continues  to  advance  along  the 
rounded  surface  of  the  lung,  to  its  anterior  margin : it  then 
passes  over  the  internal  surface  of  the  lung,  which  is  ante- 
rior to  the  pulmonary  vessels.  It  afterwards  covers  the 
front  of  the  pulmonary  vessels  and  of  the  bronchia,  and 
gets  in  a very  short  space  to  the  pericardium.  It  then 
passes  forwards  on  the  side  of  the  latter,  and  having  got 
near  its  middle  line,  goes  from  it  to  the  sternum,  and 
reaches  the  line  from  which  the  description  of  its  course 
commenced. 

There  is  no  important  difference  between  the  two  pleurae 
either  in  their  mode  of  reflection  or  in  the  organs  to  which 
they  are  attached,  so  that  the  description  of  one  will  apply 
to  either.  The  portion  of  each  pleura  covering  the  lung  is 
called  pleura  pulmonalis,  and  that  portion  which  lines  the 
thorax  is  the  pleura  costalis.  A duplicatiire  of  the  pleura 
commences  at  the  inferior  margin  of  the  pulmonary  veins, 
and  descending  as  far  as  the  diaphragm,  attaches  the  infe- 
rior portion  of  the  posterior  margin  of  each  lung  to  the  side 


144 


ORGANS  OF  RESPIRATION. 


of  the  pericardium  in  front  of  the  vertebrae.  This  duplica- 
ture  is  the  Ligamentum  Pulmonis.  It  is  longer  on  the  left 
lung  than  on  the  right  by  reason  of  the  greater  vertical 
diameter  of  the  former. 

From  what  has  been  said  it  will  now  be  readily  under- 
stood, that  the  whole  cavity  of  the  thorax  is  divided  verti- 
cally into  two  halves,  by  that  portion  of  the  two  pleurae 
which  advances  from  the  spine  towards  the  sternum.  This 
septum  is  called  the  Mediastinum,  and  the  heart,  enveloped 
by  the  pericardium,  is  placed  precisely  in  its  centre,  and 
separates  the  two  pleurae  widely  apart.  It  has  been  found 
useful  by  anatomists,  for  descriptive  purposes,  to  subdivide 
the  Mediastinum  into  three  portions  or  regions.  One  pass- 
ing from  the  front  of  the  pericardium  to  the  posterior  face 
of  the  middle  line  of  the  sternum  is  the  Anterior  Mediasti- 
num; another  passing  from  the  posterior  face  of  the  peri- 
cardium to  the  dorsal  vertebrae  is  the  Posterior  Mediasti- 
num; and  a third,  which  is  within  the  circuit  of  the  first 
ribs,  is  the  Superior  Mediastinum.  This  division,  though 
evidently  forced  and  arbitrary,  is  indispensable  to  a correct 
account  of  the  relative  situation  of  very  important  organs 
placed  between  the  two  pleurae. 

1.  The  Anterior  Mediastinum  is  less  important  than  the 
other  two;  the  portions  of  the  two  pleurae  of  which  it  con- 
sists are  almost  in  contact,  and  contain  between  them  some 
loose  cellular  substance  by  which  they  adhere  together,  and 
by  cutting  through  which,  after  a longitudinal  section  of  the 
sternum,  they  are  easily  separated  from  one  another.  The 
upper  part  of  this  septum  contains  the  remains  of  the  thymus 
gland,  its  lower  part  leaves  the  middle  line  of  the  sternum 
and  inclines  to  the  left  side;  and  when  the  sternum  is  nar- 
row below,  it  is  attached  to  the  anterior  ends  of  the  carti- 
lages of  the  lower  true  ribs. 

2.  The  Posterior  Mediastinum,  where  it  leaves  the  verte- 
brae to  reach  the  pericardium,  passes  off  from  a line  nearer 
the  heads  of  the  ribs  on  the  left  side,  than  on  the  right. 
The  descending  portion  of  the  thoracic  aorta  is  contained 


THE  LUNGS. 


145 


xvithin  this  septum,  on  the  left  side  of  the  dorsal  vertebrae. 
The  oesophagus  is  in  its  middle  in  front  of  the  vertebrae 
above,  but  in  descending  it  crosses  in  front  of  the  aorta,  and 
inclines  to  the  left  side  of  the  dorsal  vertebrae.  The  vena 
azygos  occupies  the  right  side  of  this  mediastinum,  and  after 
ascending  forms  an  arch  over  the  root  of  the  right  lung,  and 
terminates  by  joining  the  descending  cava.  The  thoracic 
duct,  after  entering  the  thorax  between  the  crura  of  the 
diaphragm,  ascends  in  front  of  the  dorsal  vertebrae  between 
the  aorta  and  the  vena  azygos,  and  behind  the  cesophagus, 
till  it  reaches  the  third  dorsal  vertebra;  it  then  inclines  to 
the  left  side,  and  mounting  into  the  root  of  the  neck  near 
the  vertebrae,  it  finally  forms  an  arch,  which,  by  advancing 
forwards,  terminates  in  the  angle  formed  by  the  junction  of 
the  left  internal  jugular  and  subclavian  veins.  The  par  Va- 
gum  Nerve,  of  both  sides,  is  also  in  the  posterior  medias- 
tinum. 

3.  The  Superior  Mediastinum  is  bounded  in  front  by  the 
tipper  part  of  the  sternum,  behind  by  the  upper  dorsal  ver- 
tebrae, and  laterally  by  the  first  ribs.  The  cavity  is  conoi- 
dal,  with  the  base  upwards,  but  is  too  peculiar  to  admit  of 
a rigid  comparison  with  any  thing  else.  The  pleurae  are 
reflected  downwards  from  the  internal  edge  of  the  first  ribs, 
not  abruptly,  but  in  a rounded  bulging  manner,  receiving 
there,  as  mentioned,  the  tip  or  apex  of  the  lungs.  In  order 
to  understand  well  the  position  of  the  pleurae,  it  must  be 
borne  in  mind  that  the  upper  rib  is  placed  very  obliquely 
downwards  and  forwards,  at  an  angle  of  about  forty-five 
degrees  with  the  spine,  consequently  the  pleura,  in  being 
reflected  from  its  whole  internal  edge,  is  much  higher  at 
the  head  of  the  rib  than  it  is  at  the  anterior  extremity  of  the 
same.  This  cavity  is  continuous  of  course  with  that  of  the 
anterior  mediastinum  in  front,  and  also  with  that  of  the 
posterior  mediastinum  behind. 

The  remains  of  the  thymus  gland  are  where  this  cavity 
joins  the  anterior  mediastinum;  a part  of  the  gland  is  indeed 
in  each  of  these  cavities  just  below  the  transverse  vein.  In 
contact  with  the  right  pleura  is  the  Descending  Vena  Cava. 

VoL.  II.— 19 


146 


ORGANS  OP  RKSPIRATION. 


The  common  trunk  of  the  Left  Subclavian,  and  Internal 
Jugular,  called  the  Transverse  Vein,  or  Vena  Innominata, 
after  crossing  in  an  oblique  descent  behind  the  upper  por- 
tion of  the  sternum,  joins  the  descending  cava  an  inch  above 
the  place  where  the  latter  penetrates  into  the  pericardium. 
Behind  the  transverse  vein  are  the  top  of  the  arch  of  the 
aorta,  the  arteria  innominata,  the  left  carotid,  and  the  left 
subclavian.  The  trachea,  with  the  oesophagus  behind  it,  de- 
scends along  the  middle  line  in  front  of  the  spinal  column. 
The  arteria  innominata  crosses  the  front  of  the  trachea  from 
left  to  right  in  ascending;  it  is  in  contact  with  the  transverse 
vein,  and  more  superficial  than  either  of  the  other  arteries. 
The  phrenic  nerve,  passing  at  the  internal  edge  of  the  sca- 
lenus anticus,  between  the  subclavian  artery  and  vein,  de- 
scends vertically  in  contact  with  the  pleura.  The  par  vagum 
passes  along  the  side  of  the  trachea,  and  afterwards  behind 
the  corresponding  bronchia  having  got  into  the  superior 
mediastinum,  between  the  subclavian  vein  and  artery:  its 
inferior  laryngeal  branch  encircles  the  subclavian  artery  on 
the  right  side,  and  the  arch  of  the  aorta  on  the  left. 

The  internal  surface  of  the  pleura  is  smooth  and  polished, 
and  is  moistened  and  kept  lubricated  by  an  unctuous  serum, 
the  natural  quantity  of  which  is  merely  sufficient  to  allow 
the  parts  to  slide  freely  upon  each  other.  In  dropsy  of  the 
chest  it  is  augmented  frequently  to  such  an  amount  as  to 
cause  the  collapse  of  the  lung,  by  pressing  upon  it. 

In  the  cellular  tissue  between  the  pleura  and  pericardium, 
as  well  as  on  the  diaphragm,  adipose  matter,  in  considerable 
abundance,  is  found  in  corpulent  persons  advanced  in  age. 

The  blood  vessels  of  the  pleura  costalis  are  derived  from 
those  which  supply  the  parietes  of  the  thorax,  as  the  inter- 
costals  and  phrenics.  They  ramify  in  the  subjacent  cellu- 
lar substance. 


BOOK  VIII. 


OF  THE  CIRCULATORY  SYSTEM. 

PART  I. 

Of  the  General  Anatomy  of  the  Circulatory  System. 

CHAPTER  I. 

GENERAL  CONSIDERATIONS. 

The  Circulatory,  or  the  Vascular  System,  consists  in  a 
congeries  of  tubes,  or  cylindrical  canals,  which  convey  the 
blood  to  and  from  every  part  of  an  animal  body,  and  there- 
fore enter  into  the  texture  or  composition  of  almost  every 
portion  of  it.  In  all  animals  there  seems  to  be  a neces- 
sity for  the  alternate  reception  and  discharge  of  alimentary 
materials;  in  the  higher  orders,  this  is  effected  through  the 
agency  of  the  vascular  system;  but  in  the  most  simple  ani- 
mals this  system  does  not  exist,  and  their  whole  fabric 
being  soft  and  permeable,  nutritious  matter  is  introduced 
by  a direct  absorption,  or  a species  of  capillary  attraction, 
after  the  manner  of  a sponge  or  any  other  porous  body,  and 
is  discharged  by  a process  equally  simple.*  It  is  probable 
that  there  are  some  parts  of  the  human  body  whose  mode 
of  nutrition  is  equally  simple;  as,  for  example,  the  articular 
cartilages,  the  hair,  nails,  and  so  on;  for  many  observations 
tend  to  prove  that  all  these  organs  have  an  interstitial  cir- 
culation. 


Hunter  on  the  Blood.  Beclard,  Anat.  Gen. 


148 


CIRCULATOKY  SYSTEM. 


In  many  animals,  the  blood  is  propelled  from  a central 
point,  called  the  heart,  to  all  parts  of  the  body,  and  then  re- 
turns again  to  the  heart.  The  first  movement  is  executed 
through  canals  called  arteries,  and  the  second  through  veins. 
It  is  the  most  simple  scheme  by  which  a circulation  can  be 
carried  on  through  a sanguiferous  system,  and  requires  a heart 
with  only  two  cavities;  one  for  propelling  blood  into  the 
arteries,  or  departing  tubes,  and  another  as  a reservoir  for 
receiving  the  blood  of  the  returning  tubes,  or  the  veins.  The 
two  cavities  must  be  near  each  other,  and  have  a valvular 
opening  between  them,  which  will  permit  the  blood  to  pass 
from  the  venous  into  the  arterial  reservoir;  but  not  from  the 
arterial  into  the  venous.  A circulation  of  this  simple  cast  is 
found  in  fish  and  in  animals  generally,  whose  respiration  is 
effected  on  the  surface  of  the  body;  but  in  man  and  in  other 
warm  blooded  animals,  where  respiration  is  carried  on  in- 
teriorly by  means  of  the  lungs,  their  circulatory  apparatus 
is  double;  one  part  being  for  the  lungs,  and  the  other  part 
for  the  body  generally. 

In  man,  the  heart  consists  of  four  cavities:  two  auri- 
cles or  reservoirs  of  venous  blood,  and  two  ventricles  into 
which  the  venous  blood  is  transmitted,  and  which  in  their 
functions,  may  be  compared  to  the  forcing  pump  of  a fire-en- 
gine. The  circulation  is  effected  in  the  following  manner: 
The  blood  contained  in  the  right  auricle  of  the  heart  flows 
into  the  right  ventricle,  and  from  the  latter  it  is  forced 
through  the  pulmonary  artery  into  the  lungs.  It  returns 
from  the  lungs  through  the  four  pulmonary  veins,  and  is  re- 
ceived into  the  left  auricle  of  the  heart;  from  the  latter  it 
flows  into  the  left  ventricle,  and  is  propelled  from  it  into  the 
aorta.  The  aorta  then  distributes  it  through  the  whole  body 
by  an  infinitude  of  small  branches;  from  the  latter  it  is  col- 
lected, by  corresponding  veins,  into  two  trunks,  the  Ascend- 
ing and  the  Descending  Cava.  The  ascending  vena  cava 
brings  the  blood  from  the  lower  extremities  and  from  the  ab- 
domen; the  descending  vena  cava  brings  the  blood  from  the 
head  and  neck,  the  upper  extremities,  and  the  parietes  of  the 
thorax.  These  two  trunks  finally  discharge  the  blood  into 


general  considerations. 


149 


the  cavity  from  which  it  started,  to  wit,  the  right  auricle. 
The  same  round  is  then  renewed,  and  continues  to  be  repeat- 
ed during  the  whole  course  of  life.  It  is  customary  for  ana- 
tomists to  call  the  rout  of  blood  from  the  right  ventricle, 
through  the  lungs,  to  the  left  auricle  inclusively,  the  lesser 
or  the  pulmonary  circulation;  and  that  which  begins  at  the 
left  ventricle,  goes  through  the  whole  body,  and  ends  in  the 
right  auricle,  the  greater  circulation. 

The  blood  contained  in  the  veins  of  the  greater  circulation, 
in  the  right  auricle  and  ventricle,  and  in  the  pulmonary  ar- 
tery, is  of  a dark  brown  or  reddish  colour;  while  that  con- 
tained in  the  pulmonary  veins,  in  the  left  auricle  and  ventri- 
cle, and  in  the  aorta  and  its  ramifications,  is,  from  being  vi- 
vified by  respiration,  of  a carmine  or  Vermillion  complexion. 
The  celebrated  Bichat  has,  upon  these  differences  of  colour, 
founded  his  division  of  the  whole  circulating  system  into  two 
parts;  one  containing  black  blood,  “Systeme  vasculaire  a 
sang  noire;”  the  other  red  blood,  “ Systeme  vasculaire  a sang 
rouge,”  This  division  having  general  physiology  for  its 
object,  affords  a well  marked  distinction,  suited  to  such  dis- 
cussions. 

The  lymphatics  also  are  a part  of  the  circulatory  system, 
but  as  they  do  not  commonly  convey  red  blood,  the  consid- 
eration of  them  will  be  brought  up  subsequently.  They 
take  a very  active  part  in  the  animal  economy,  whether  na- 
tural or  diseased,  and  seem,  in  many  actions,  to  be  the  anta- 
gonists of  the  arteries;  while  the  veins  are  much  more  pas- 
sive, being  principally  employed  in  returning  the  blood  to 
the  heart.”* 

The  largest  vascular  trunks  are  situated  near  the  centre  of 
the  body  and  limbs,  on  the  side  upon  which  flexion  is  accom- 
plished, while  those  near  the  surface  are  generally  small. 
Most  commonly  there  are  one  artery,  one  or  two  veins,  and 
several  lymphatics,  all  together. 

The  arterial  system  in  its  external  configuration  may  be 
compared  to  a tree,  the  trunk  of  which  is  attached  to  the 
heart,  and  which  by  a continued  succession  of  divisions  and 


* Hunter,  loc,  cit 


150 


CIKCULATOKY  SYSTEM. 


subdivisions  reaches  to  every  part  of  the  body.  There  are 
no  means  of  estimating  rigidly  the  collective  area  of  the 
bi’anches  in  proportion  to  that  of  the  trunk,  but  a little  ob- 
servation on  the  size  of  the  primitive  branches  will  satisfy 
one  of  a great  excess  on  the  part  of  the  latter;  and  as  the 
rule  is  maintained  throughout,  there  must  finally  be  an  im- 
mense disproportion.  We  have  then  reason  to  believe,  that 
if  all  the  branches  were  assembled  into  a single  cavity, 
this  cavity  would  be  somewhat  like  a cone,  the  apex  of  which 
would  be  next  to  the  heart.  The  same  rule  holds  in  regard 
to  the  venous  system,  it  being  observed,  however  that  the 
latter  has  two  trunks  connected  with  the  heart  instead  of 
one.  The  general  rule  is  therefore  established  throughout 
the  vascular  system,  that  the  collective  area  of  the  branches 
is  always  greater  than  that  of  the  trunk  from  which  they 
proceed.  By  the  same  rule  the  circulation  in  the  branches 
must  be  more  languid  than  in  the  parent  trunks,  as  this  cir- 
culation is  retarded  both  by  additional  friction  and  by  having 
to  fill  up  a larger  canal.  The  course  of  rivers  exemplifies 
this  continually,  while  confined  to  narrow  channels  they 
rush  tumultuously  through  them,  but  when  they  begin  to  ex- 
pand themselves  into  capacious  basins,  or  to  be  divided  into 
a multitude  of  smaller  channels,  the  current  becomes  slower, 
and  in  some  cases  imperceptible,  though  the  fact  is  clear, 
that  an  equal  volume  of  water  is  every  where  descending  in 
the  same  period  of  time. 

The  moisture  conferred  upon  all  parts  by  the  circulation 
of  the  blood,  bears  a sufficient  analogy  to  the  effects  of  ir- 
rigation upon  ground.  The  water  may  be  conducted  to  the 
latter  by  a canal,  which  is  finally  divided  into  an  infinitude 
of  streamlets,  which  ramify  every  where,  and  from  the  po- 
rosity of  their  beds  permit  lateral  percolation,  so  that  the 
whole  field,  even  to  its  most  minute  atom,  is  kept  moist- 
ened. The  streamlets  afterwards  successively  assemble 
again  into  a single  canal,  which  bears  off  their  superabun- 
dant water.  From  the  nature  of  the  particles  of  blood, 
many  of  them  ai'e  confined  to  their  proper  channels  and 
can  never  pass  off  by  percolation  into  the  tissues,  through 


GENERAL  CONSIDERATIONS. 


151 


which  the  blood  vessels  ramify.  This  may  be  proved  by 
the  fact  that  the  red  globules  of  blood  have  a diameter  of 
from  the  two-thousandth  to  the  five-thousandth  part  of  an 
inch,  a size  inconsiderable  as  it  is,  yet  too  large  to  permit 
their  flowing  through  elementary  fibres  or  atoms;  whereas 
serum  or  the  water  of  the  blood  may,  from  the  extreme 
fineness  of  the  particles,  be  absorbed  by  any  tissue  what- 
ever; a circumstance  entirely  unquestionable,  both  from 
daily  observation,  as  for  example,  in  soaking  a piece  of 
dried  meat  or  a bone;  and  from  the  reflection  that  the  air  it- 
self, will  hold  a certain  quantity  of  water  in  solution. 

A question  then  arises  whether  the  moisture  of  parts  not 
•supplied  with  red  globules  of  blood,  comes  in  the  living 
body  exclusively  from  infiltration  or  from  a peculiar  set  of 
vessels  called  exhalents,  often  talked  of,  but  as  yet  never 
seen  ? That  the  lateral  porosities  of  blood  vessels  are  large 
enough  to  allow  watery  fluids  to  exude,  is  readily  proved 
by  injecting  water  into  the  blood  vessels  of  a limb,  or  of 
any  other  part,  when  the  latter  invariably  becomes  oedema- 
tous.  It  is  in  this  way  even  possible  to  inundate  a living 
animal,  as  I have  seen  accomplished  by  M.  Magendie,  in 
Paris.  This  moisture  requires  a change,  and  by  continued 
additions  would  become  superabundant:  as  it  has  been 
thrown  out  of  the  common  current  of  the  circulation  and 
could  not  be  removed  in  any  other  way,  the  lymphatic  sys- 
tem has  therefore  been  added  for  the  purpose.  In  the  low- 
er orders  of  animals,  who  are  destitute  of  blood  vessels,  the 
interstitial  change  of  moisture  goes  on  without  lymphatics. 
No  part  of  the  human  body  is  exempt  from  moisture,  but 
it  is  furnished  by  smaller  streams,  and  is  also  less  abundant 
in  some  textures  than  in  others;  for  example,  though  blood 
vessels  susceptible  of  conveying  red  blood  do  ramify 
through  tendons  and  ligaments,  yet  they  are  not  numerous 
apparently,  not  more  so,  indeed,  than  what  is  sufficient  to 
keep  up  by  a deposite  of  serum,  the  flexibility  of  those  parts. 
The  vascularity  of  a part  during  life  may  be  ascertained  by 
a simple  process  after  death,  the  most  vascular  always  lose 
proportionately  of  their  bulk  by  drying,  for  example,  a 


152 


CIRCTTLATOEr  SYSTEM. 


muscle  shrinks  more  than  a tendon,  a gland  more  than  a 
muscle. 

Besides  the  operation  of  the  lymphatics,  much  of  the  super- 
abundant moisture  is  carried  off  by  insensible  perspiration 
and  evaporation  from  the  surface  of  the  body;  the  latter 
process,  however,  is  much  restrained  by  the  peculiar  cha- 
racter of  the  cuticle,  without  which  it  would  become  ex- 
cessive, probably  so  much  so  as  to  exceed  any  supply  of 
fluid  through  the  stomach. 

The  red  globules  of  the  blood,  besides  their  less  obvious 
uses,  unquestionably  serve  to  inspissate  the  serous  or  watery 
part,  by  an  intimate  mixture  with  it,  and  thereby  put  a cer- 
tain restraint  upon  its  extravasation.  - They  also,  from  their 
size,  serve  to  keep  open  the  channels  through  which  the 
blood  circulates.  So  much  associated  is  the  existence  of 
red  globules  with  regular  blood  vessels,  that  there  are  but 
few  exainples  of  animals  having  the  former,  without  also 
having  the  latter;  whereas,  in  animals,  whose  circulating 
fluid  has  not  red  globules,  but  is  a mere  serum,  the  entire 
destitution  of  regular  blood  vessels  is  very  common,  and 
their  circulation,  if  the  name  be  deserved,  consists  simply 
in  the  transmission  of  moisture  from  one  pore  to  another, 
as  occurs  in  a rag  or  in  a sponge,  by  mere  capillary  attrac- 
tion. Such  animals  form  a numerous  class  in  the  chain  of 
organized  beings,  and  have  a gelatinous  consistence. 

A remarkable  feature  in  the  vascular  system,  both  arteries 
and  veins,  is  the  disposition  of  trunks  to  run  into  one  another; 
or,  in  other  words,  to  form  an  anastomosis,  whereby  if  the 
blood  should  be  cut  off  by  one  rout,  it  may  still  be  supplied 
through'another.  These  communications  are  frequent  in  the 
head,  in  the  neck,  in  the  thorax,  in  the  abdomen,  and  in  the 
extremities;  they  exist,  indeed  wherever  the  blood  vessels 
do,  and  become  more  numerous  as  the  blood  vessels  are 
smaller,  or  more  removed  from  the  centre  of  the  circulation. 
It  is  unnecessary  here  to  specify  instances,  as  the  more  re- 
markable ones  will  be  mentioned  at  a proper  time.  But  some 


general  considerations. 


153 


estimate  may  be  made  of  their  importance,  and  of  the  facility 
of  communication  established  by  them,  when  it  is  remem- 
bered that  cases  have  occurred  of  obstructed  aorta  without 
the  circulation  ceasing  in  the  parts  of  the  body  beyond  it; 
the  same  has  occurred  to  the  venae  cavas,  and  to  the  thoracic 
duct  also.  '* 

The  extreme  vascular  ramifications  are  called  Capillaries, 
( Vasa  Capillaria, ) and  they  form  the  connexion  between  the 
arteries  and  veins;  or,  by  being  intermediate  to  the  two, 
they  are  the  ultimate  terminations  of  the  arteries,  and  the 
commencing  roots  of  the  veins.  From  the  extreme  tenuity 
of  these  vessels,  it  is  impossible  to  indicate  where  the  arteries 
terminate  and  the  veins  begin;  yet  the  continuity  of  the  two 
has  been  repeatedly  demonstrated,  by  throwing  injections 
from  the  one  into  the  other  system,  and  by  microscopical 
observations  made  on  the  transparent  parts  of  living  animals, 
as  the  mesentery  and  web  foot  of  frogs,  and  the  tail  of  fishes. 
These  facts  are  sufficiently  substantiated  by  tbe  observations 
of  Malpighi,  Lewenhoeck,  Prochaska,  and  a crowd  of  others; 
yet  there  are  anatomists  who  hold  a contrary  doctrine,  and 
admit  the  parenchyma  of  the  ancients  (an  indefinable  some- 
thing, conceived  however  to  be  spongy)  as  a point  qf  ter- 
mination for  tbe  arteries,  and  of  commencement  for  the 
veins. 

Though  the  capillaries  are  all  too  fine  to  be  seen  distinctly 
without  a microscope,  yet  they  are  found  to  have  several 
gradations  of  size.  The  largest  of  them,  or  those  which 
only  escape  the  naked  eye,  experience  successive  divisions, 
whereby  their  diameters  are  reduced  from  admitting  a file  of 
several  globules  of  blood  to  the  calibre  of  one  globule  only.t 
The  capillaries  have  also  frequent  anastomoses  with  one 
another.  Sometimes  the  artery  is  simply  doubled  on  itself, 
and  immediately  becomes  a vein:  on  other  occasions,  several 
capillary  arteries  run  into  the  same  vein.  When  these  com- 
munications are  unduly  enlarged,  they  constitute  what  has 
been  called  by  Mr.  J ohn  Bell  the  aneurism  from  anastomosis; 

* Bedard,  Anat.  Gen. 

VoL.  IL— 20 


j Bedard,  loc.  dt. 


CIIICITLATOKV  Si'STKM. 


lol 

a frequent  mark  in  young  children,  and  which,  when  it  has 
developed  itself  fully,  has  a spongy  structure  resembling  the 
erectile  tissues,  as  the  corpus  cavernosum  penis,  &c.  As 
there  is  a double  circulation,  so  there  is  a double  capillary 
system,  one  for  the  lungs  and  the  other  for  the  body  gene- 
rally;  to  these  may  be  added  a third,  which  exists  in  the 
liver,  between  the  hepatic  extremities  of  the  vena  portarum 
and  the  hepatic  veins. 

The  texture  of  the  capillary  vessels  is  too  fine  to  admit 
of  much  scrutiny,  but  they  appear  as  simple  cylindrical  ex- 
cavations in  the  substance  of  the  part  to  which  they  belong. 
It  is  not  improbable,  that  they  may  be  uninterrupted  conti- 
nuations of  the  internal  coat  of  the  arteries  into  that  of  the 
veins.  They  have  striking  powers  of  extension  and  of  con- 
traction, and  are  easily  irritated.  An  emotion  of  the  mind, 
as  a sentiment  of  shame  or  a feeling  of  resentment,  quickly 
causes  those  of  the  face  to  become  turgid  with  blood.  Lo- 
cal stimuli  cause  congestions  in  them.  Cold,  the  application 
of  a weak  acid,  or  fear,  causes  them  to  contract.  Though, 
under  the  influence  of  the  heart,  they  are  less  so  than  larger 
vessels.  Their  innumerable  channels  cause  a comparatively 
languid  circulation  of  the  blood  in  them,  for  reasons  men- 
tioned; and  by  furnishing  it  with  more  places  of  contact 
with  their  parietes,  put  it  more  under  nervous  influence 
than  it  is  elsewhere. 

These  vessels  are  not  equally  abundant  in  all  the  textures 
of  the  body.  Their  quantity  may  be  ascertained  by  the  red- 
ness which  a part  acquires  by  inflammation,  as  well  as  by 
fine  injections:  the  latter  proof  is  preferable,  as,  in  the  for- 
mer, it  is  difficult  to  distinguish  them  from  the  extravasa- 
tions which  also  occur  at  the  same  time.  The  celebrated 
injections  of  Ruysch,  from  their  unusual  minuteness,  in- 
duced him  to  think  that  every  solid  portion  of  the  body 
was  vascular,  yet  he  admitted  that  some  portions  were  more 
vascular  than  others,  thereby  conceding  to  his  antagonists, 
that  some  points  at  least  were  not  formed  by  blood  vessels. 
In  the  microscopical  examinations  on  living  animals,  for 
example  the  frog,  it  is  seen  that  in  their  feet  the  smallest 
capillaries  are  separated  by  distinct  intervals,  while  in  the 


general  considerations. 


155 


mucous  membrane  of  the  lungs  the  finest  needle  cannot 
have  its  point  inserted  without  opening  several  of  them.  * 
The  younger  an  animal  is  the  more  vascular  are  its  parts: 
but  on  the  contrary,  as  it  advances  in  age,  the  proportion  of 
parts  not  susceptible  of  injection  increases,  while  the  ca- 
pillaries diminish  in  number.  In  cold  blooded  animals  it 
is  very  evident,  that  some  of  these  capillaries  or  arterio- 
venous communications  are  large  enough  to  admit  a file  of 
several  red  globules  abreast,  while  others  allow  a single  file 
only.  As  a general  rule,  their  diameter  may  be  stated  at 
from  one  to  five  globules  of  red  blood,  t 

The  nutrition  of  the  body  depends  upon  an  alternation  of 
exhalation  and  of  absorption;  but  it  is  still  undetermined, 
whether  there  be  any  vessels  whatever  whose  especial  ofiice 
is  that  of  exhalation,  and  which  produce  the  several  secre- 
tions and  exhalations.  If  there  be  such,  they  are  generally 
designated  by  the  term  exhalents,  and  their  diameters  are 
too  small  to  transmit  the  red  globules  of  blood;  their  func- 
tion is  consequently  to  give  passage  to  the  serous  particles 
only.  This  subject  has  been  much  agitated  by  anatomists, 
and  marshals  the  best  authorities  on  both  sides.  Among 
the  distinguished  advocates  in  the  affirmative,  are  Boer- 
haave,  Haller,  and  Bichat;  and  opposed  to  them  are  Pro- 
chaska,  Mascagni,  and  Richerand.  The  leading  facts  of  the 
former  are:  The  microscopical  observations  of  Lewenhoeck, 
who  speaks  of  vessels  admitting  only  serous  globules;  the 
phenomena  of  inflammation,  which  render  red,  parts  na- 
turally white  and  transparent;  the  difficulty  of  conceiving 
how  the  nourishment  of  certain  parts  can  be  maintained, 
whose  capillary  system  of  red  blood  is  so  limited,  in  pro- 
portion to  points  not  susceptible  of  it.  The  opinion  of  Mas- 
cagni and  others  to  the  contrary  is:  That  those  exhalents,  if 
they  existed,  should  be  seen  readily,  inasmuch  as  they  are 
within  the  range  of  a microscope,  whose  powers  enable  one 
to  examine  a body  much  smaller  than  a red  globule  of 
blood;  that  injections  should  penetrate  them,  instead  of  being 
limited  to  vessels  whose  existence  is  sufficiently  confirmed 


* Bedard.  Anat.  Gen. 


I Bedard,  loc.  cit, 


156 


CIRCULATORY  SYSTEM. 


by  examination  in  the  living  state;  that  if  during  inflamma- 
tion they  do  seem  to  be  injected  with  red  blood,  the  ap- 
pearance is  delusive,  and  depends  upon  the  existing  capil- 
laries being  dilated  so  as  to  receive  moi'e  red  blood  than 
usual,  upon  the  formation  of  new  vessels,  and  upon  sangui- 
neous infiltration;  and,  as  to  membranes  naturally  white, 
as  the  conjunctiva,  the  colour  depends  upon  the  capillaries, 
while  in  a healthy  state,  being  so  small  that  they  do  not 
admit  the  red  globules  in  a file  sufficiently  numerous  to  be 
perceived  by  the  eye,  the  globules  being  probably  then 
conducted  in  a series  of  one  only,  or  in  a single  file,  like  a 
string  of  beads.  It  is,  therefore,  much  more  reasonable  not 
to  admit  the  existence  of  vessels  which  it  is  very  doubtful 
whether  any  one  has  seen. 

When  a watery  injection  is  pushed  into  a blood  vessel, 
it  in  a little  time  shows  itself  as  a fine  dew  upon  the  surface 
of  the  serous  and  mucous  membranes;  in  the  cellular  mem- 
brane, and  elsewhere.  According  to  many  anatomists,  it  has 
gone  through  the  system  of  exhalents,  and  indeed  presents 
itself  to  sight  in  very  much  the  same  way,  that  exhalation 
occurs  in  the  living  state.  From  the  view  which  has  just 
been  taken,  it  becomes  more  probable,  that  this  perspiration 
is  executed  through  the  interstices  or  pores  of  the  vessels. 
In  the  dead  state  it  is  merely  a mechanical  result,  a simple 
straining  of  the  fluid;  whereas,  in  the  living  body  it  is  a vital 
function,  continually  modified  by  the  peculiar  vital  powers 
of  the  organ  or  membrane  where  it  occurs;  and,  therefore, 
presents  itself  under  the  form  of  the  different  secretions. 
The  question  of  the  exhalents  being  a distinct  set  of  vessels, 
does  not,  however,  appear  to  be  one  of  much  consequence; 
because,  if  they  do  exist,  they  must  be  very  short  and  very 
small;  and  the  assumption  of  their  existence  does  not  throw 
any  light  upon  the  function  of  secretion.  For  the  latter  is 
still  an  incomprehensible  vital  process,  and  as  far  as  we 
have  any  idea  about  it,  it  is  quite  as  easy  to  conceive  of  its 
being  performed  in  the  parietes  of  the  capillaries,  as  in  the 
mouths  of  a distinct  set  of  vessels,  whose  length  is  too  short 
to  admit  of  an  estimate. 

Besides  the  supposed  existence  of  a general  system  of  ex- 


GENERAL  CONSIDERATIONS.  157 

Iialent  vessels,  some  anatomists  have  thought  that  there  was 
a species  of  them  acting  particularly  as  nutritive  vessels. 
According  to  Boerhaave  every  part  must,  therefore,  be 
vascular.  Mascagni  thought  that  the  extreme  arterial  rami- 
fications are  not  only  furnished  with  exhaling,  but  also  with 
nutritive  porosities,  and  that  there  are  every  where  orifices 
of  absorbing  vessels,  to  contain  the  nutritive  molecules. 
The  theories  of  Bichat  and  of  Prochaska,  do  not  differ  ma- 
terially from  the  latter.  Whatever  may  be  the  mode  of  ex- 
istence, and  the  rout  of  nutriment  to  the  several  parts  of 
the  body,  the  operations  involved  are  entirely  too  subtle 
even  for  microscopic  observation.  We,  therefore,  can  only 
understand  in  a general  way,  that  the  blood  vessels  deposite, 
and  the  lymphatics  absorb,  by  invisible  avenues  in  the  cel- 
lular substance,  the  molecules  of  composition  and  of  decom- 
position in  our  organs.*  It  is  to  this  power  that  the  name 
of  vital  force  has  been  given,  and  especially  that  of  the  force 
of  formation  {nisus  formativus. ) 

CHAPTER  II. 

or  THE  TEXTURE  OF  THE  ARTERIES. 

The  arteries,  though  commonly  said  to  be  cylindrical 
canals,  are  not  exactly  so,  but  as  they  recede  from  the  heart 
increase  somewhat  in  diameter,  even  where  they  do  not 
send  off  any  branches.  In  this  way  the  arteries  of  the  um- 
bilical chord  are  evidently  larger  as  they  get  nearer  the 
placenta;  and  the  spermatic  arteries  of  a bull  as  they  get 
nearer  to  the  testicle.  Observations  made  on  the  carotid  ar- 
teries of  the  camel  and  of  the  swan  by  Mr.  Hunter, t tend  to 
prove  the  same  disposition  in  them.  It  is  probable  that  the 
rule  extends  to  all  arteries  throughout  the  system,  but  it 
cannot  be  ascertained  with  so  much  certainty,  because  of 
the  close  succession  of  branches  which  they  send  off. 


* Bedard,  loc.  dt. 


f On  the  Blood  and  Inflammation. 


15S 


CmCULATORr  SYSTEM. 


Arteries  have  within  themselves  a power  of  increase  con- 
nected with  the  exigencies  of  the  part  to  which  they  go; 
thus  the  uterine  arteries  increase  much  in  their  capacity 
during  pregnancy,  while  the  hypogastric,  from  which  they 
are  derived,  augment  inconsiderably,  and  the  primitive 
iliacs  not  in  an  appreciable  manner.  In  animals  of  the  deer 
kind,  whose  horns  are  deciduous,  the  same  augmentation 
of  arterial  trunks  occurs  while  the  horn  is  growing.  Tu- 
mours are  supplied  in  the  same  way.  But  in  all  these  cases 
after  the  exigency  is  passed  the  vessels  diminish  to  their 
primitive  size. 

With  the  exception  of  the  semilunar  valves  at  the  orifice 
of  the  pulmonary  artery  and  of  the  aorta,  there  are  no  others 
in  the  whole  arterial  system.  These  valves  permit  the 
blood  to  pass  in  the  direction  of  the  circulation,  but  not 
backwards,  as  they  are  closed  immediately  upon  the  cessa- 
tion of  the  contraction  of  the  ventricles.  The  tricusped 
valve,  and  the  semilunar  of  the  pulmonary  artery,  are  na- 
turally not  so  perfect  in  their  closure  as  those  on  the  other 
side  of  the  heart,  but  permit  a small  quantity  of  blood  to 
retrograde.!  As  life  advances  the  valves  of  the  aorta  are 
much  disposed  to  ossifications  and  derangements  of  diffe- 
rent kinds;  which  render  them  much  less  perfect,  than  those 
of  the  pulmonary  artery. 

The  arteries  are  composed  of  three  coats;  an  external,  a 
middle,  and  an  internal. 

The  External  Coat,  also  called  cellular  or  nervous,  is  in 
fact,  condensed  cellular  substance  formed  into  a cylinder. 
Its  fibres  run  in  every  direction  so  as  to  be  perfectly  inter- 
woven with  one  another.  The  exterior  periphery  of  this 
coat  is  continued  into  the  adjacent  cellular  substance,  but  its 
internal  face  is  united  more  closely  to  the  middle  coat,  not 
however  so  tightly  as  to  prevent  a slight  sliding  of  the  one 
upon  the  other,  and  to  forbid  their  easy  separation  by  a 
knife.  Scarpa  is  not  disposed  to  admit  this  as  one  of  the 
coats  of  arteries,  and  says  that  it  only  serves  as  an  exterior 

* Hunter,  lot,  cit. 


TEXTTTKE  OF  THE  ARTERIES. 


159 


envelope,  and  retains  them  in  their  places.  This  coat  ma- 
nifests its  fibrous  character  in  not  being  disposed  to  secrete 
fat,  and  is  more  distinct  in  the  large  arterial  trunks.  It  has 
considerable  strength  and  elasticity,  both  circularly  and 
longitudinally,  and  is  remarkable  for  its  whiteness.  If  an 
artery  be  surrounded  by  a tightly  drawn  ligature,  the  mid- 
dle and  the  internal  coats  will  be  completely  cut  through 
by  it,  while  the  external  coat  remains  entire.  This  coat 
answers  then  the  purpose  of  a strong  investing  fascia,*  in 
which  respect  it  may  be  considered  as  a sheath  to  the  pro- 
per arterial  structure,  though  the  term  sheath  is  commonly 
applied  to  the  cellular  membrane  on  its  outer  side. 

The  Middle  Coat  of  the  arteries  is  called  the  Muscular, 
the  Proper,  the  Tendinous,  and  so  on.  It  is  of  a light  yel- 
lowish tinge,  and  decreases  continually  in  thickness,  with 
but  few  exceptions,  from  the  heart  to  the  ends  of  the  arte- 
riesj  it  is,  however,  proportionately  thicker  in  the  small 
arteries  than  in  the  large  ones.  Its  fibres  are  circular,  but 
do  not  individually  perform  the  circuit  of  the  vessel.  They 
are  parallel  to  each  other,  and  adhere  laterally  by  very  slen- 
der ties.  In  the  larger  arteries  this  coat  may  be  divided 
into  several  laminae,  though  the  division  is  entirely  artifi- 
cial. There  are  no  longitudinal  fibres  whatever  in  it,  the 
consequence  of  which  is,  that  an  artery  divested  of  its  ex- 
ternal coat,  yields  more  readily  in  the  direction  of  its  length 
than  of  its  circumference. 

The  middle  coat  has  a firmness,  whereby,  even  when  an 
artery  is  emptied,  the  cylindrical  shape  is  still  retained.  Its 
character  seems  to  be  the  result  of  a mixture  of  elastic  and 
of  muscular  properties  derived  from  a state  of  tissue  entire- 
ly peculiar;  but  which  some  anatomists  have  been  very  de- 
sirous of  ranging  under  the  head  of  muscles,  others  under 
that  of  ligaments,  and  a third,  under  both  united.  The  ce- 
lebrated Jno.  Hunter,  whose  observations  were  generally 
made  with  the  most  scrupulous  attention  to  perfect  exacti- 
tude, were  often  repeated  so  as  to  make  one  confirm  ano- 


* Jones  on  Hemorrhage. 


1(30 


CIRCULATORY  SYSTEM. 


ther;  and  who  has  received  that  sanction  of  greatness  in 
which  one’s  posthumous  reputation  becomes  more  exalted 
than  the  living;  bestowed  much  attention  on  this  subject. 
He  was  induced  to  believe  that  this  middle  coat  was  formed 
by  a muscular  lamina  internally,  and  an  elastic  one  exter- 
nally; which  distinction  might  be  rendered  evident  by  cut- 
ting a contracted  artery  through  transversely , when  the 
muscular  coat  would  be  found  projecting  beyond  the  other. 
He  acknowledges,  however,  that  he  never  could  discover 
the  direction  of  the  muscular  fibres:  though  he  supposed 
them  to  be  oblique,  because  their  degree  of  contraction  was 
greater  than  a straight  muscle  could  produce. 

The  elastic  contraction  of  an  artery,  is  manifested  both 
in  the  direction  of  its  length  and  of  its  circumference;  for, 
when  put  upon  the  stretch  in  either  way,  it  has  the  ability 
of  returning  to  its  original  dimensions  after  the  distending 
force  ceases.  The  Muscular  contraction,  however,  only 
occurs  in  the  circumference,  and  not  at  all  in  the  length; 
by  it  the  calibre  of  arteries  is  reduced  to  a very  small  dia- 
meter, if  an  animal  be  slowly  bled  to  death.  If,  in  this 
contracted  condition,  an  artery  be  slit  open  longitudinal- 
ly, the  elastic  coat  will,  at  the  cut  margin,  project  beyond 
the  other,  which  Mr.  Hunter  considers  as  another  way  of 
ascertaining  the  existence  of  the  two  tunics.  But  if  this 
same  artery  be  then  stretched  transversely,  the  muscular 
coat  will  project  beyond  the  other,  for  the  reason,  that  if  a 
muscle,  after  death,  be  elongated  by  force,  it  has  no  power 
of  returning  from  that  state,  but  will  remain  precisely  as  it 
is:  whereas,  elasticity  being  a property  of  matter  enjoyed 
quite  as  fully  in  the  dead  as  in  the  living  state,  the  elastic 
coat  of  the  artery  returns  to  the  medium  condition. 

Mr.  Hunter,  with  the  view  of  satisfying  himself  on  these 
several  points,  had  a horse  bled  to  death,  so  as  to  obtain  the 
vessels  at  their  minimum  of  contraction.  A circular  suc- 
tion of  the  aorta  measured,  at  first,  five  inches  and  a half, 
and,  on  being  stretched,  it  lengthened  to  ten  inches  and  a 
half;  being  let  alone,  it  contracted  to  six  inches,  at  which 
it  remained  stationary;  the  difference  between  six  inches 


TEXTURE  OF  THE  ARTERIES. 


161 


and  ten  and  a half  was  then  the  amount  of  its  elastic  power, 
w ile  only  half  an  inch  of  contraction  was  due  to  the  mus- 
cular stratum,  or,  in  other  words,  an  eleventh  of  the 
whole. 

A section  of  the  iliac  artery,  measuring  two  inches  in 
circumference,  on  being  allowed  to  contract  after  stretch- 
ing, measured  two  and  one-third  inches;  it,  therefore,  gained 
one-sixth  the  amount  of  its  muscular  contraction.  A sec- 
tion of  the  axillary  artery  gained  one-eighth — of  the  caro- 
tid, two-thirds — of  the  radial  artery,  doubled  its  primitive 
extent.  From  all  which  the  inference  was  drawn,  that  the 
power  of  recovery  in  a vessel  is  greater,  in  proportion  as  it 
is  nearer  the  heart,  but  lessens  as  the  distance  increases, 
which  shows  the  decrease  of  elastic,  and  the  increase  of 
muscular  power. 

The  elastic  coat  gives  a middle  state  to  an  artery,  or  has 
a continued  tendency  to  it;  if,  therefore,  the  artery  be  too 
much  dilated,  it  contracts  it,  and  if  it  be  too  much  contract- 
ed, it  dilates  it,  all  of  which  is  readily  exemplified  by  a cy- 
linder of  gum  elastic,  which,  whether  compressed  or  dilated, 
has  only  one  state  of  repose,  to  which  it  immediately  re- 
turns on  being  left  to  itself.  Mr.  Hunter  supposed,  that  a 
certain  degree  of  elasticity  is  continued  to  the  very  end  of 
every  artery,  from  this  quality  being  better  suited  to  sus- 
tain a permanent  resistance  than  muscular  power;  as  a pipe 
of  lead,  from  its  want  of  elasticity,  finally  becomes  stretched 
and  useless  under  the  pressure  of  a column  of  water,  where- 
as, one  of  iron,  from  being  elastic,  always  reacts  efficiently. 
It  is  this  elasticity  in  the  arteries,  which  causes  the  blood, 
at  a little  distance  from  the  heart,  to  flow  through  them  in 
a continued  jetting  stream  when  they  are  opened,  although 
it  is  supplied  to  the  aorta  by  interrupted  strokes.  In  this 
way,  as  the  artery  is  more  distant  from  the  heart,  the  stream 
becomes  proportionately  regular. 

“ The  muscular  power  of  an  artery  renders  a smaller 
force  of  the  heart  sufficient  for  the  purposes  of  circulation; 
for  the  heart  need  only  act  with  such  force  as  to  carry  the 
blood  through  the  larger  arteries,  and  then  the  muscular 
VoE.  II. — 21 


162 


CIKCULATOKY  SYSTEM. 


power  ol  the  arteries  takes  it  up,  and  as  it  \^’e,  removes 
the  load  of  blp%l'  while  the  heart  is  dilating.  ' ql^.confiiTna- 
tion  of  this  remark,  it  is  observable  in  animal^  vVkose  arte- 
ries are  very  muscular,  that  the  heart  is  proportionably 
weaker,  so  that  the  muscular  power  of  the  vessels  becomes 
a second  part  to  the  heart,  acting  where  the  power  of  the 
heart  begins  to  fail,  and  increasing  in  strength  as  that  de- 
creases in  power.”* 

The  Internal  Coat  of  the  arteries  is  designated  by  the 
terms  Nervous  and  Arachnoid.  It  is  continued  from  the 
ventricles  of  the  heart,  in  the  left  one  of  which  it  is  of  un- 
usual thickness.  It  is  the  duplipation  of  this  membrane 
with  some  fibres  interposed,  that  composes  the  semilunar 
valves  of  the  aorta  and  of  the  pulmonary  artery.  Its  in- 
ternal face  is  smooth,  polished,  and  moistened  with  a kind 
of  humidity  which  permits  the  blood- to  flow  through  with 
diminished  friction.  In  the  larger  arterial  trunks,  some 
small  longitudinal  wrinkles  are  observable  in  it;  and  when 
an  artery  has  been  cut  through,  as  in  amputation,  it  is  dis- 
posed to  retract  in  small  transverse  wrinkles.  It  is,  there- 
fore, not  very  extensible,  but  has,  according  to  the  experi- 
ments of  Sir  Everard  Home,t  a considerable  degree  of 
solidity  and  strength. 

Ossifications  of  this  membrane  are  very  frequent  after 
the  age  of  sixty. 

In  addition  to  the  tunics  mentioned,  cellular  substance, 
vessels,  and  nerves  enter  into  the  structure  of  arteries. 

The  Cellular  Substance  is  not  abundant,  and  serves  prin- 
cipally to  unite  the  sides  of  the  circular  fibres  to  one  ano- 
thei’,  and  to  join  the  internal  to  the  middle  coat. 

The  Vessels  ( Vasa  tUrteriarum)  consist  both  in  arteries 
and  in  veins,  and  come  from  the  adjacent  trunks,  instead  of 
from  those  on  which  they  ramify.  They  may  be  made 
very  distinct  by  a fine  injection,  or  by  laying  them  bare  in 

■ Hunter,  loc.  cit. 

t Transactions  for  the  Improvement  of  Medical  and  Surgical  Knowledge, 
vol.  i. 


TEXTURE  OP  THE  ARTERIES. 


163 


the  living  body;  when  in  a little  time  after  exposure,  they 
begin  evidently  to  carry  red  blood,  and  to  grow  turgid  as 
in  inflammation.  The  difference  in  the  colour  of  the  blood 
■distinguishes  these  arteries  from  the  same  kind  of  veins. 
Both  arteries  and  veins  may  be  traced  very  well  into  the 
middle  coat,  but  not  upon  the  internal,  though  the  changes 
which  occur  in  the  latter,  from  disease  and  upon  the  appli- 
cation of  ligatures,  prove  clearly  that  exhalation  and  ab- 
sorption is  continually  going  on  there.  For  in  inflamed  ar- 
teries, an  exhalation  is  seen  upon  their  internal  surface,  and 
when  a coagulum  has  been  produced  by  ligature,  it  is  final- 
ly absorbed. 

The  Nerves  of  the  ar-teries,  according  to  Wrisberg  and 
Bedard,  are  numerous  and  considerable,  form  around  them 
a plexus  resembling  that  of  the  par  vagum  around  the  oeso- 
phagus, and  follow  them  into  the  interior  of  our  organs, 
with  the  exception  of  the  brain;  which  has  them  only  to  its 
surface.  They  are  jiroportionately  more  abundant  in  the 
aortic  than  in  the  pulmonary  system;  also  upon  the  smaller 
than  upon  the  larger  arteries.  The  arteries  of  the  head,  of 
the  neck,  of  the  thorax,  and  of  the  abdomen,  are  supplied 
from  the  sympathetic  nerve,  while  those  of  the  extremities 
are  supplied  from  the  nerves  of  the  spinal  marrow. 

The  passing  of  the  blood  through  the  arteries  is  accom- 
panied v/ith  a pulsating  motion,  which  for  the  most  part,  is 
exactly  synchronous  with  the  contraction  of  the  left  ven- 
tricle, and  depends  upon  an  increased  quantity  of  blood 
thrown  into  them  at  the  moment.  The  dilatation  of  the 
artery  may  be  both  seen  and  felt;  ‘‘but  were  we  to  judge 
of  the  real  increase  of  the  artery  by  this,  we  should  deceive 
ourselves;  for  when  covered  by  integuments,  the  apparent 
effect  is  much  greater  than  it  really  is  in  the  artery  itself; 
for  in  laying  such  an  artery  bare,  the  nearer  we  come  to  it, 
the  less  visible  is  its  pulsation;  and  when  laid  entirely  bare, 
its  motion  is  hardly  either  to  be  seen  or  felt.  This  appa- 
rent diastole  of  the  artery  is  augmented  in  proportion  to  the 
solid  matter  covering  it,  whence  tumours  over  large  arte- 
ries have  considerable  motion  given  to  them,  and  have  often 


164 


CIRCULATORr  SV$TEM. 


been  supposed  to  be  aneurismal.  Arteries,  in  fact,  during 
their  diastole  or  dilatation,  increase  much  more  in  length 
than  in  width,  and  are  thrown  into  a serpentine  course;  in- 
stead, therefore,  of  the  term  diastole,  it  should  rather  be 
called  the  elongated  state.”*  Mr.  Parry,  of  Bath,t  has 
denied  that  the  arteries  dilate  at  all  during  their  diastole;  his 
opinion,  however,  is  peculiar,  though,  in  an  experiment 
performed  some  years  ago  upon  the  carotid  artery  of  a calf, 
its  correctness  appeared  to  me  then  to  be  fully  proved. 

There  is  no  part  of  the  human  body  which  presents  more 
frequent  varieties,  in  different  individuals,  than  the  arteries. 
These  varieties  are  found,  in  their  place  and  manner  of  ori- 
gin, in  position,  and  in  the  number  of  their  ramifications. 
They  are  comparatively  rare  in  the  trunks  of  the  first  or- 
der, more  common  in  those  of  the  second,  and  still  more 
usual  in  those  of  the  third  and  fourth.  From  these  causes, 
discrepancies  are  continually  found  in  the  descriptions  of 
the  most  approved  authorities,  and  must  last  so  long  as  wri- 
ters repose  upon  a partial  experience,  instead  of  referring  to 
what  has  been  most  generally  observed. 

o> 

CHAPTER  III. 

OF  THE  TEXTURE  OF  THE  VEINS. 

The  veins,  from  their  duty  of  I’eceiving  the  blood  in  all 
parts  of  the  body  from  the  extreme  arteries,  and  returning 
it  to  the  heart,  by  successively  collecting  it  into  the  two 
venae  cavae,  may  be  more  appropriately  compared  to  the 
roots  of  a tree,  than  to  its  branches.  The  variations  in 
them,  as  well  as  their  anastomoses,  are  more  frequent  than 
in  the  arteries. 

They  are  more  numerous  than  the  arteries;  foi’,  in  addi- 
tion to  two  venous  trunks  attending  each  artery  wherever 

* .1.  Hunter,  loc,  cit. 

Experimental  Inquiiy  on  the  Pulse,  1816 — 1819. 


TEXTURE  OP  THE  VEINS. 


165 


the  structure  of  the  part  is  intended  for  locomotion,  as  in 
the  extremities,  and  in  some  places  upon  the  trunk  of  the 
body,  there  is  a very  abundant  class  of  veins  which  are 
superficial  or  subcutaneous,  and  which,  when  filled  pro- 
perly with  injecting  matter,  form  a fine  vascular  network 
over  the  whole  surface  of  the  body.*  These  superficial 
veins,  in  some  places,  form  trunks  even  larger  than  such  as 
attend  the  arteries,  and  especially  in  the  extremities.  Be- 
sides the  excess  in  number,  the  veins  which  attend  the  ar- 
teries (Venae  Comites)  have  a capaciousness  which,  in  many 
cases,  is  double  that  of  the  latter.  From  these  several  cir- 
cumstances, it  results  that  the  area  of  the  venous  system 
vastly  exceeds  that  of  the  arterial. 

In  some  cases  the  veins  follow  precisely  the  course  of 
the  arteries,  one  for  one,  as  in  the  greater  number  of  the 
viscera  of  the  abdomen,  where  they  have  common  points 
of  entering  and  departure  Sometimes  two  arteries  dis- 
charge into  one  vein,  as  in  the  penis,  the  clitoris,  and  the 
umbilical  chord;  sometimes  they  pursue  a course  entirely 
different  from  the  arteries,  as  in  the  pia  mater.  For  the 
most  part  they  are  less  tortuous  than  the  arteries. 

The  veins,  when  injected,  assume  a cylindrical  shape, 
yet  they  differ  materially  from  the  arteries,  in  having  much 
thinner  coats,  and  in  being  so  pliable  that  they  collapse  by 
their  own  weight.  In  the  lower  extremities,  however,  near 
the  feet  and  upon  them,  as  the  veins  sustain  the  pressure  of 
a long  column  of  blood;  they  have  additional  thickness  and 
strength,  so  as  to  approximate  them  more  to  the  arterial 
structure.  This  provision  will  be  found  occurring  in  most 
places  where  they  have  much  duty  to  perform. 

“ They  are  similar  to  the  arteries  in  their  structure,  be- 
ing composed  of  an  elastic  and  muscular  substance;  the 
elasticity  preserves  them  in  some  degree  in  a middle  state, 
although  not  so  pei’fectly  as  it  does  in  the  arteries.  The 
muscular  power  adapts  the  veins  to  the  various  circum- 
stances, which  require  the  area  to  be  within  the  middle 
state,  and  assists  the  blood  in  its  motion  towards  the  heart”! 

* Pauli  Mascagni  Anatom.  Unlv'ers.  Pisis,  1823.  f Hunter,  loc.  cit. 


166 


CIRCULATORY  SYSTEM. 


The  External  Coat  is  thinner  and  not  so  strong  as  that  of 
the  arteries;  in  other  respects,  the  resemblance  is  sufficiently 
close  not  to  require  any  particular  comment. 

The  Middle  Coat,  near  the  entrance  of  the  larger  veins 
into  the  heart,  is  distinctly  muscular.  * It  is  formed  of  soft 
extensible,  fibres,  many  of  which,  when  the  vein  is  held  up 
to  the  light,  appear  longitudinal,  while  the  most  internal  are 
circular;  there  are  difficulties,  however,  in  the  separation  of 
these  fibres,  which  prevent  their  course  from  being  accu- 
rately ascertained.  Bichat  and  Meckel  assert,  that  the  whole 
of  them  are  longitudinal,  and  that  there  are  none  circular. 

This  coat,  in  the  human  subject,  is  much  thicker  in  the 
system  of  the  ascending  than  of  the  descending  cava;  it  is 
also  thicker  in  the  superficial  than  in  the  deep-seated  veins. 
In  some  subjects  it  is  much  better  developed  than  in  others. 
In  certain  parts  of  the  body  it  is  entirely  deficient,  as  in  the 
sinuses  of  the  dura  mater,  and  has  its  place  supplied  by  this 
membrane;  the  same  deficiency  exists  in  the  sinuses  of  the 
bones. 

The  Internal  Coat  is  more  delicate  and  extensible  than 
the  corresponding  one  of  the  arteries,  is  less  liable  to  rup- 
ture, and  less  disposed  to  ossification.  It  is  thrown  into  a 
considerable  number  of  duplications,  forming  valves.  Each 
valve  is  of  a semicircular  shape;  is  connected  by  its  convex 
edge  to  the  vein,  while  the  straight  edge  is  loose,  and  turned 
towards  the  heart.  When  the  veins  are  injected  backwards, 
these  valves  may  be  forced  in  the  larger  trunks,  and  give 
them  a knotted  appearance.  The  valves  are  commonly  in 
pairs,  but  in  certain  veins,  as  the  crural  and  the  iliac,  there 
are  three  of  them  together;  very  rarely  do  they  amount  to 
four.  In  some  instances  there  is  but  a single  one;  this  ar- 
rangement is  more  frequent  at  venous  orifices,  as  the  great 
coronary  vein  of  the  heai’t,  the  vena  cava  ascendens,  the 
vena  azygos.  They  are  frequently  found  reticulated  as  if 
they  had  been  lacerated,  whence  it  has  been  supposed  that 

* Bedard,  loc.  cit. 


TEXTURE  OF  THE  VEINS. 


167 


the  fibres  which  cross  the  sinuses  of  the  dura  mater  are  an 
elementary  approach  to  them. 

The  valves  are  more  abundant  in  the  superficial  than  in 
the  deep-seated  veins,  but  they  do  not  exist  every  where. 
There  are  none  in  thp  branches  of  the  vena  portarum,  ex- 
cepting the  vasa  brevia;  none  in  the  brain,  in  tbe  spinal 
marrow,  in  the  umbilical  vein,  the  cervical  veins,  the  kid- 
neys, womb,  ascending  and  descending  cava,  or  in  the  me- 
dian vein.  The  valves  are  proportionately  more  abundant  in 
the  lower  extremities. 

From  the  tenuity  of  the  parietes  of  the  veins,  the  blood 
may  be  readily  distinguished  circulating  through  them. 
Their  coats,  like  those  of  the  arteries,  are  vascular,  or  have 
the  vasa  vasorum.  The  arteries  come  from  the  nearest  small 
trunks,  while  the  corresponding  veins  do  not  empty  imme- 
diately, but  secondarily,  into  the  trunk,  whose  parietes  they 
supply. 

Their  elasticity,  both  transversely  and  longitudinally, 
is  well  marked;  but  they  are  not  so  extensible  in  the  latter 
direction  as  the  arteries,  while  they  are  more  so  transversely. 
There  can  be  no  donbt  of  their  spontaneous  powers  of  con- 
traction, for  it  is  abundantly  proved  by  their  diminishing 
much  in  volume  upon  the  application  of  cold;  moreover, 
when  a venous  trunk,  distended  with  blood,  is  intercepted 
by  two  ligatures  and  then  punctured,  it  empties  itself  en- 
tirely and  rapidly. 

The  circulation  in  the  veins  is  produced,  in  a principal 
degree,  by  the  contraction  of  the  heart;  their  own  contrac- 
tion may  also  favour  this  motion,  as  well  as  lateral  pressure 
from  contiguous  parts,  as  the  movement  of  the  blood  in  the 
smaller  arteries  is  so  continued  as  to  be  almost  without  pul- 
sation, so  the  latter  disappears  entirely  in  the  veins.  It  is  not 
clear  that  this  circumstance  depends  exclusively  on  the  fric- 
tion experienced  by  the  blood  in  passing  through  the  capil- 
laries, but  is  probably  rather  owing,  as  Mr.  Hunter  has 
suggested,  to  the  veins  receiving  their  blood  from  different 


16S 


CIRCULATORV  SYSTEBI. 


arteries,  some  of  whose  channels  are  more  circuitous  than 
others  and  consequently  their  blood  arrives  at  different 
times.  The  momentum  of  the  heart  then,  even  if  it  did  im- 
pinge upon  those  channels,  would  not  be  synchronous  upon 
the  venous  trunk,  but  would  be  divided  in  such  a way  as  to 
produce  a tremour  or  confused  motion.  The  larger  veins, 
however,  have  near  the  heart  a pulsation  during  the  contrac- 
tion of  the  auricles,  arising  from  the  arrest  of  their  circula- 
tion at  the  moment.  During  inspiration,  the  vacuum  created 
in  the  thorax  hurries  on  the  blood  to  the  heart,  but  in  expi- 
ration it  is  somewhat  impeded.  * 

It  has  sometimes  happened,  that  a large  vein  near  the 
heart  being  opened  by  an  accident  or  an  operation  a strong 
inspiration  has  caused  the  introduction  of  air,  which,  being 
cai’ried  to  the  heart,  has  produced  instant  death.  It  lately 
occui’red  in  Paris,  to  the  celebrated  surgeon  Dupuytren. 


CHAPTER  IV. 

OF  THE  BLOOD. 

The  Blood,  in  the  human  subject,  and  in  many  animals, 
is  of  a red  colour.  It  is  about  the  consistence  of  thin  size, 
has  a peculiar  smell,  a nauseous  and  slightly  saline  taste, 
and  is  somewhat  heavier  than  water,  its  specific  gravity 
being  about  105.  Its  quantity  is  variously  estimated  at 

* I'his  ancient  observation  has  lately  been  renewed,  with  additional  inte- 
rest and  details,  by  M.  Barry  of  Faris.  See  a report  of  MM.  Cuvier  and 
Dumeril,  concerning  the  Influence  of  the  Atmosphere  on  the  Circulation  of 
the  Blood,  in  the  PhUadelplua  Journal  of  the  Medical  and  Physical  Sciences, 
July,  1826.  M.  Barry  has  probably  assigned  too  much  importance  to  this 
influence,  as  it  is  ceiiain  that  the  circulation  may  go  on  veiy  well  where  no 
vacuum  is  produced  at  intervals  in  the  thorax;  for  example,  in  the  feetus, 
in  incubation,  and  in  fish. 


THE  BLOOD. 


169 


from  eight  to  one  hundred  pounds,  so  that  there  would  seem 
to  be  no  very  exact  means  of  ascertaining  this  point. 

So  long  as-  it'  continues  to  circulate,  or  while  it  is  still 
flowing  from  an  opened  vessel,  it  has,  to  common  inspection, 
the  appearance  of  a homogeneous  fluid;  yet,  after  it  has  been 
drawn  a few  minutes,  and  permitted  to  remain  at  rest,  it  as- 
sumes a thick  gelatinous  condition,  expressed  by  the  term 
coagulation,  and  by  which  it  ceases  to  be  any  longer  fluid. 
This  change  has  scarcely  taken  place,  when  a spontaneous 
separation  follows  whereby  it  is  resolved  into  a'  watery  part 
called  Serum,  and  into  a thick  condensed  mass  called  Cruor 
or  Crassamentum.  The  serum  first  shows  itself  on  the  sur- 
face of  the  coagulum,  in  small  drops,  which  quickly  increas- 
ing in  number  and  size,  finally  run  together,  and  form  a mass 
of  fluid  exceeding  considerably  that  of  the  crassamentum. 
The  coagulation  begins  on  the  surface  of  the  mass,  and  by  a 
thin  pellicle,  which  shows  itself  in  three  or  four  minutes; 
commonly  at  the  end  of  twenty  minutes  the  coagulation  is 
complete  throughout,  but  this  rule  varies  according  to  the 
state  of  the  body  at  the  moment;  and  the  coagulation  is  more 
protracted  when  the  quantity  of  blood  is  large  and  has  been 
drawn  through  a large  orifice,  than  where  it  is  small,  and 
has  been  evacuated  through  a small  orifice.  The  separation 
into  serum  and  crassamentum,  though  sufficiently  evident 
after  a few  hours,  yet  requires  some  days  for  its  complete 
accomplishment;  for  the  coagulum  still  continuing  to  con- 
tract, expels  more  and  more  of  the  serum. 

The  peculiar  complexion  of  the  blood  depends  upon  a red 
colouring  matter  consisting  in  globules.  This  matter  does 
not  seem  to  be  an  indispensable  constituent,  as  many  ani- 
mals are  entirely  deprived  of  it,  and  such  as  naturally  are 
possessed  of  it,  may  have  its  quantity  very  much  reduced 
by  repeated  bleedings.  The  colouring  matter  is  generally 
an  ingredient  of  the  crassamentum,  so  that  the  whole  of  the 
latter  has  a red  appearance;  yet  there  are  some  conditions 
of  the  body  in  which  a spontaneous  separation  of  it  takes 
place,  more  or  less  completely.  For  example,  in  inflam- 
matory diseases  the  blood  does  not  coagulate  so  soon  as  in 
VoL.  ir.  — 22 


170 


CIIICULATORY  SYSTEM. 


health;  and  the  red  globules,  from  being  naturally  heavier 
than  the  other  constituents  of  the  crassamentum,  subside  to 
its  bottom  and  leave  it  of  a white  semitransparent  colour. 
It  is  this  white  part  upon  which  depends  the  whole  proper- 
ty of  coagulating,  and  which  has  been  called  coagulating 
lymph.  We  have  therefore  three  constituents  of  blood 
manifested  by  its  own  spontaneous  changes;  the  serum,  the 
red  globules,  and  the  coagulating  lymph. 

Coagulation,  contrary  to  popular  opinion,  is  not  assisted  by 
cold,  but  rather  retarded  by  it;  heat  assists  it.*  If  the  heat 
be  raised  to  120°,  blood  will  coagulate  rive  minutes  sooner 
than  if  left  at  its  natural  standard,  and  even  sooner  than  if  its 
temperature  be  reduced  to  50°.  If  blood  be  frozen  quick- 
ly, before  it  has  time  to  coagulate,  on  being  thawed  it  re- 
turns to  the  fluid  state,  and  will  coagulate  afterwards.  The 
contact  of  air  does  not  produce  coagulation.  Dr.  Physick, 
in  order  to  ascertain  this  point  conclusively,  took  a glass 
tube,  which  had  a stop  cock  at  each  end,  and  attached  one 
of  its  ends  to  the  vein  of  a dog.  A current  of  blood  was 
then  conducted  through  the  tube,  and  while  it  was  flowing, 
the  far  stop  cock  was  closed,  and  immediately  afterwards 
the  other;  thus  a column  of  blood  was  obtained  which  had 
not  touched  the  air.  After  permitting  it  to  remain  a pro- 
per time,  the  tube  was  broken  asunder,  and  the  blood 
found  coagulated  as  usual.  Rest  is  not  indispensable  to  the 
process;  for  blood,  if  shaken  in  a vial,  will  still  coagulate. 
The  division  of  the  blood  into  small  masses  expedites  coa- 
gulation. Therefore,  when  it  flows  slowly  from  the  ves- 
sels, falls  from  some  height,  or  runs  for  a distance  over  the 
surface  of  a dish,  it  coagulates  sooner  than  under  opposite 
circumstances.  The  latter  are  then  auxiliary  to  the  blood 
manifesting  the  sizy  coat,  one  of  the  concomitants  of  inflam- 
mation; because,  if  the  coagulation  be  very  rapid,  it  will  pre- 
vent the  constituents  of  the  crassamentum  from  separating 
from  one  another,  by  entangling  the  red  globules  in  the  coa- 
gulating lymph. 

After  death  the  blood  is  coagulated  in  the  veins,  though 
' Hunter  on  the  Blood.  Ilewson. 


SEKTTM  OP  THE  BLOOD. 


171 


not  so  perfectly  or  generally  as  is  supposed,  for  there  are 
no  subjects  which  do  not  bleed  from  the  large  veins,  when 
the  latter  are  opened. 

There  are  many  modes  of  death  which  prevent  entirely 
the  coagulation  of  the  blood  in  the  vessels,  for  example, 
where  life  is  destroyed  by  a paroxysm  of  excessive  anger; 
by  electricity;  by  lightning;  by  a blow  upon  the  stomach; 
by  certain  fevers  of  a typhoid  character.  Many  chemical 
articles  prevent  its  coagulation  on  being  mixed  with  it.  ■ 


. SECT.  I. OP  THE  SERUM  OP  THE  BLOOD. 

Serum  is  common  to  the  blood  of  all  animals,  and  is  con- 
sidered, by  Mr.  Hunter,  to  be  more  abundant  in  such  as 
have  red  globules.  It  is  generally  of  a lighter  specific  gra- 
vity than  the  crassamentum.  I have,  however,  often  seen 
the  latter  floating  in  it,  which  shows  the  contrary  in  some 
instances.  Though  its  separation  commonly  depends  upon 
the  coagulation  of  the  latter,  yet  that  process  is  not  indis- 
pensably necessary,  as  was  once  witnessed,  by  Mr.  Hunter, 
in  a lady,  in  whom  the  serum  was  disengaged  from  the  coa- 
gulating lymph,  while  the  latter  was  yet  in  a fluid  state. 
The  phenomena  of  dropsy  also  prove  the  same  point. 

Serum,  though  very  limpid,  is  not  so  much  so  as  water. 
It  is  a light  yellow  or  straw  colour,  varying  somewhat  in 
different  subjects.  It  contains  a large  quantity  of  albumen, 
or  matter  resembling  the  white  of  an  egg.  It  also  consists 
of  water,  of  soda  uncombined,  and  of  some  of  the  salts  of 
soda,  the  presence  of  all  which  may  be  manifested  in  seve- 
ral ways.  For  example,  when  exposed  to  a heat  of  140 
degrees  of  Fahrenheit,  it  becomes  opaque,  and  at  160  or 
165  coagulates  firml)''.  During  this  process  a great  deal  of 
air  is  disengaged  from  it.  It  is  also  coagulated  by  spirits 
of  wine,  by  all  the  mineral  acids,  by  corrosive  sublimate, 
and  by  many  other  articles.  Mr.  Brande  considers  it  as 
an  albuminate  of  soda,  with  an  excess  of  its  base,  and  that 
its  fluidity  depends  on  the  quantity  of  soda;  when,  there- 
fore, the  latter  is  removed  or  neutralized  by  an  acid,  the 
albumen  coagulates.  Under  the  action  of  tlie  galvanic  pile, 


112 


CIRCULATORY  SYSTEM. 


like  the  influence  of  heat,  the  soda  jiroduces  mucus,  by 
blending  with  a part  of  the  albumen;  and  the  remainder  of 
the  latter,  not  being  able  to  retain  its  fluidity  after  the  ab- 
duction of  the  soda,  coagulates. 

This  mucus  is  probably  the  part  which  Mr.  Hunter  speaks 
of  as  retaining  its  fluidity  when  other  portions  of  the  serum 
are  coagulated  by  heat.  It  is  observed  in  meat  either  roasted 
or  boiled,  and  comes  from  it  as  a thin,  limpid  fluid,  some- 
what tinged  with  the  red  globules.  The  older  the  animal 
is,  the  greater  is  its  comparative  quantity;  in  lamb  there  is 
scarcely  any  of  it,  whereas,  in  mutton  five  or  six  yeai’S  old, 
it  is  abundant;  the  same  rule  seems  to  hold  in  regard  to  the 
human  subject.  This  serosity.  or  mucus  is  coagulable  by 
Goulard’s  Extract.  * 

The  serum  is  not  always  transparent,  but  sometimes 
wheyish  and  thin;  when  it  settles,  it  often  throws  up  a 
white  scum  like  cream.  This  more  frequently  occurs  in 
pregnant  women,  though  it  is  not  confined  exclusively  to 
either  sex,  or  to  any  known  condition  of  body.  The  speci- 
fic gravity  of  the  globules  composing  this  scum  varies;  for 
tho’.igxx  it  generally  floats  on  the  surface  of  the  serum,  it 
. CCS  not  always:  it  also  sometimes  swims,  and  on  other  oc- 
casions sinks  in  water.  It  has  been  erroneously  considered 
as  chyle  not  yet  assimilated,  or  as  absorbed  fat  or  oil.  It 
is,  probably,  this  substance  which  also  presents  itself  under 
the  form  of  microscopic  globules  in  the  coagulum  of  serum; 
and,  when  serum  has  been  kept  for  several  days,  is  depo- 
sited in  the  form  of  globules  at  its  bottom.  These  globules 
present  a singular  motion  of  ascent  and  descent  in  the  se- 
rum; upon  the  application  of  heat  to  it  by  holding  it  in  the 
hand.  It  is  said  that  albumen,  coagulated,  presents  a very 
close  resemblance  to  fibrine.t 

The  presence  of  soda  uncombined  in  the  serum,  is  rea- 
dily ascertained  by  tincture  of  litmus  or  of  red  cabbage, 
which  are  both  made  green  by  it.  Sulphur  combined  with 
ammonia,  is  also  found  in  it.  Owing  to  the  presence  of  sul- 
phur, serum  has  the  effect  of  blackening  silver  when  left 


Hunter,  loc.  cit. 


f Bedard,  loc.  cit. 


BED  GLOBULES  OF  THE  BLOOH. 


173 


in  it,  and  also  has  its  power  of  dissolving  the  oxydes  of 
mercury,  iron,  copper,  and  other  metallic  preparations. 

SECT.  II. OF  THE  COAGULATING  LYMPH  OF  THE  BLOOD. 

Coagulating  lymph,  or  fibrine,  when  circumstances  are 
suitable  for  collecting  it,  freed  from  the  red  globules,  offers 
the  appearance  of  a semitransparent  body  of  a very  light 
drab  colour;  it  is  elastic  and  strong,  and  when  subjected  to 
the  microscope  has  the  appearance  of  muscular  fibres,  by 
being  composed  of  colourless  globules.  Like  muscle,  it 
also,  when  macerated  in  water,  resolves  itself  into  those 
globules  before  it  putrefies. 

If  the  blood,  while  flowing  from  an  animal,  be  collected, 
and,  at  the  same  moment,  stirred  round  and  round  with  a 
rough  stick,  the  fibrine  will  gather  upon  the  latter  in  a 
fibrous  form,  so  as  to  resemble  a mass  of  entangled  and 
knotted  packthread.  The  fibrine  may  be  afterwards  washed 
almost  white,  and  at  any  rate,  so  as  to  clear  it  entirely  from 
the  red  globules. 

The  fibrine,  when  dried,  loses  greatly  in  its  bulk  and 
weigTit,  by  the  evaporation  of  the  serum  from  it,  so  that  the 
proportion  which  it  seems  to  bear  to  the  whole  mass  of 
blood  is  much  less  considerable  than  one  would  suppose 
from  seeing  it  in  the  simple  coagulated  state. 

“The  coagulating  lymph  of  the  blood  being  common, 
probably,  to  all'  animals,  while  the  red  particles  are  not,  we 
must  suppose  it  from  jthis  alone  to  be  the  most  essential  part; 
and,  as  we  find  it  capable  of  undergoing,  in  certain  circum- 
stances, spontaneous  changes,  which  are  necessary  to  the 
growth,  continuance,  and  preservation  of  the  animal;  while 
to  the  other  parts  we  cannot  assign  any  such  uses,  we  have 
still  more  reason  to  suppose  it  the  most  essential  part  of  the 
blood  in  every  animal.”* 

SECT.  III. OF  THE  RED  GLOBULES  OP  THE  BLOOD. 

The  particles  of  blood  upon  which  its  red  colour  depends 
are,  by  the  majority  of  observers,  considered  to  be  globular, 


* Hunter,  loc.  cit. 


174 


CIRCULATORY  SYSTEBI. 


and  while  tlie  blood  circulates  they  float  about  in  the  lymph 
and  serum.  They  are  of  the  same  size  in  animals  of  the 
same  species,  and  have  no  tendency  to  run  into  each  other, 
as  globules  of  mercury  would.  They  are  plastic,  by  which 
they  can  assume  an  elliptical  shape  when  they  circulate 
through  vessels  of  a very  small  size. 

According  to  the  microscopical  observations  of  Mr.  Bauer, 
each  globule  is  one  two-thousandth  part  of  an  inch  in  dia- 
meter, but  Capt.  Kater  does  not  consider  it  to  exceed  one 
five-thousandth  part  of  an  inch.  * There  seems,  however, 
to  be  a great  uncertainty  in  these  estimates  of  form  and  of 
size,  inasmuch  as  different  observers  do  not  agree  among 
themselves.  Father  Della  Torre  considered  them  as  flat 
circles  or  rings  with  a perforation  in  the  centre,  while  Mr. 
Hewson,  in  ascribing  the  same  shape,  represented  them  as 
hollow  or  vesicular,  with  a red  dot  in  the  middle.  Mr. 
Bauer,  on  the  contrary,  considers  that  the  dot,  or  colouring 
matter  of  the  globule,  is  placed  upon  its  periphery.  As  the 
colour  is  supposed  to  depend  upon  particles  of  iron.  Dr. 
John  Mason  Good  has  wittily  suggested,  that,  according  to 
Mr.  Hewson,  we  have  the  wheels  of  life  moving  upon  iron 
axles,  whereas,  according  to  Mr.  Bauer,  they  only  have 
ii’on  tiers,  t 

It  has  been  observed  that  the  red  globules  are  the  heaviest 
part  of  the  mass  of  blood,  and  are  therefore  always  disposed 
to  subside  to  the  bottom  of  the  crassamentum,  though  from 
the  quick  coagulation  of  the  latter,  they  can  seldom  do  it 
before  they  become  entangled  in  it,  and  thereby  fixed  to  a 
certain  place.  They  do  not  invariably  retain  their  form, 
but  are  readily  dissolved  in  water.  They  are,  of  course,  in- 
soluble in  serum.  Urine  does  not  dissolve  them;  neither 
does  a solution  of  muriate  of  soda,  of  sal  ammoniac,  epsom 
salts,  nitre,  diluted  sulphuric  or  muriatic  acid,  the  latter, 
however,  deprives  them  of  colour. 

The  solution  of  red  globules  in  water  is  manifested  by  the 
mixture  becoming  of  a fine  transparent  red,  and  the  process 
takes  place  almost  immediately.  On  the  contrary,  when  the 


* Phil.  Trans.  1818. 


I Study  of  Medicine,  vol.  II.  p 25. 


RED  GLOBULES  OP  THE  BLOOD.,  175 

globules  refuse  to  be  dissolved  a muddy  mixture  is  formed. 
When  they  are  dried  in  serum,  and  afterwards  soaked  again 
in  it,  they  do  not  resume  the  globular  form.  They  have 
more  substance  than  the  coagulating  lymph,  for  they  do  not 
lose  so  much  of  their  bulk  by  drying. 

Notwithstanding  the  doubts  that  have  been  raised  on  the 
subject,  it  seems  now  to  be  very  well  ascertained^  that  iron 
is  the  colouring  principle  of  the  red  globules  of  the  blood, 
though  it  cannot  be  detached  in  the  coloured  state,  owing  to 
the  absolute  necessity  of  using  strong  heat,  or  concentrated 
acids  to  destroy  the  substance  with  which  it  is  combined. 
The  iron  is  an  oxyde  with  a small  quantity  of  the  sub-phos- 
phate, but  a knowledge  of  this  fact  does  not  enable  the  che- 
mist to  imitate  red  globules  by  mixing  these  chemical  sub- 
stances with  albumen.  The  process  by  which  Berzelius 
obtains  iron  from  the  blood,  consists  in  placing  a clot  of  the 
latter  upon  blotting  paper,  whereby  its  serum  is  absorbed. 
The  clot  being  afterwards  put  into  water,  its  colouring  mat- 
ter is  dissolved,  while  the  lymph  remains  entire;  by  remov- 
ing then  the  lymph  and  evaporating  the  water,  the  colour- 
ing matter  is  obtained,  which,  on  being  reduced  to  ashes, 
renders  about  one  two-hundredth  part  of  its  weight  in  iron. 

The  chemists  also  inform  us,  that  fibrine,  albumen,  and 
the  colouring  mattei*,  all  resemble  one  another  so  closely, 
that  they  are  only  modifications  of  one  and  the  same  sub- 
stance; and,  that  each  of  them  yields,  upon  decomposition, 
phosphate  and  carbonate  of  lime,  though  these  ingredients 
cannot  be  detected  by  tests  applied  to  the  entire  mass  of 
blood. 

“It  is  difficult  to  determine  by  what  means  the  iron,  or 
the  sulphur,  or  the  elementary  principles  of  calcareous  earth, 
obtain  an  existence  in  the  blood.  If  these  materials  were 
equally  diffused  throughout  the  surface  of  the  earth,  we 
might  easily  conceive  that  they  were  introduced  through 
the  medium  of  food.  But  as  this  is  not  the  case;  as  some 
regions,  like  New  South  Wales,  at  least,  on  this  side  the 
Blue  mountains,  contain  no  limestone  whatever,  and  others, 
no  iron  or  sulphur,  while  all  these  are  capable  of  being  ob- 


176 


CIRCULATORY  SYSTEM. 


tained  apparently  as  freely  from  the  blood  of  the  inhabitants 
of  such  regions,  as  from  that  of  those  who  live  in  quarters 
where  such  materials  enter  largely  into  the  natural  products 
of  the  soil;  it  is,  perhaps,  most  reasonable  to  conclude  that 
they  are  generated  in  the  laboratory  of  the  animal  system 
itself,  by  the  all-controlling  influence  of  the  living  princi- 
ple.”^ 

The  red  globules,  according  to  the  opinion  of  Mr.  Hunter, 
from  not  being  pushed  into  the  extreme  arteries,  where  the 
coagulating  lymph  reaches,  and  from  not  being  found  in  all 
animals,  do  not  contribute  to  the  growth  and  to  the  repair 
of  the  system.  But  they  seem  to  be  connected  with  sti-ength, 
in  such  animals  as  have  them,  as  the  strength  acquired  by 
exercise  increases  their  proportion  and  occasions  them  to  be 
carried  abundantly  into,  parts  which  previously,  from  a de- 
bilitated state,  received  them  but  partially,  if  at  all.  This 
» fact  is  well  known  to  graziers,  who  keep  their  quantity  in 
certain  animals,  as  veal,  reduced  by  quietude  and  frequent 
bleeding. 

Their  source  is  not  understood,  though  many  conjectures 
on  the  subject  have  been  hazarded.  Mr,  Hunter’s  opinion 
was,  that  they  do  not  appear  to  be  formed  in  those  parts  of 
the  blood  already  produced,  but  rather  to  rise  up  in  the  sur- 
rounding parts;  as,  in  the  incubated  egg  they  exist  in  the 
form  of  a zone  composed  of  dots,  previously  to  the  forma- 
tion of  vessels.  This  fact  ought  to  quiet  all  speculations  about 
their  coming  from  the  spleen,  thymus  gland,  and  so  on. 


* Good,  loc.  clt. 


BOOK  vin. 


PART  II. 

Special  Anatomy  of  the  Circulatory  System. 
CHAPTER  I. 

OF  THE  HEART.  AND  PERICARDIUM. 

The  Heart,  {Cor,)  the  centre  of  the  circulation,  is  situated 
in  the  thorax,  between  the  sternum  and  the  spine;  being 
bounded  on  its  sides  by  the  lungs,  and  below  by  the  tendi- 
nous centre  of  the  diaphragm.  It  is  a hollow  muscular  or- 
gan. 

The  heart  is  of  a conoidal  shape,  but  flattened  on  the  sur- 
face, which  lies  upon  the  diaphragm.  This  flat  surface  is  on 
a horizontal  line  with  the  lower  end  of  the  second  bone  of 
the  sternum;  the  base  of  the  cone  is  towards  the  vertebrae, 
and  looks  obliquely  backwards  to  the  right  side,  while  the 
apex  is  about  the  junction  of  the  left  fifth  rib  with  it§  carti- 
lage. Being  placed  between  the  right  and  the  left  pleura,  in 
the  mediastinum,  it  is  surrounded  by  its  own  proper  capsule 
called  the  pericardium.  Its  common  weight  is  about  six 
ounces.  Its  greatest  length,  to  wit,  that  from  the  apex  to 
the  base  is  about  five  and  a half  inches,  four  of  which  are 
taken  up  by  the  ventricles;  its  base  is  about  three  and  a half 
inches  in  diameter. 

The  heart  is  divided  into  four  cavities;  two  auricles  and 
two  ventricles;  the  places  where  the  partitions  are  placed 
between  these  cavities  are  marked  on  the  surface  of  the 
heart  by  fissui’es,  sufficiently  distinct  to  be  immediately  re- 
cognised. The  two  auricles  form  the  base  of  the  heart,  the 
VoL.  II.— 23 


17S 


CIRCULATORY  SYSTEM. 


ventricles  constitute  its  body,  and  the  left  ventricle,  by  be- 
ing extended  somewhat  beyond  the  right,  forms  the  apex. 
The  right  auricle  and  the  right  ventricle  are  the  tw<o  cavi- 
ties which  are  nearest  to  the  right  side  of  the  body,  while 
the  left  auricle  and  the  left  ventricle  are  the  two  cavities 
nearest  to  the  left  side.  It  will,  however,  be  understood, 
from  the  general  observations  already  made,  that  the  rela- 
tive situation  of  these  cavities  is  such  that  the  right  ones  are 
in  front  of  the  others,  and  present  obliquely  forwards  to  the 
right  side,  while  those  on  the  left  side  look  obliquely  back- 
wards to  the  left  side.  This  position  of  the  heart  causes  it 
to  encroach  more  upon  the  left  cavity  of  the  thorax  than  it 
does  on  the  right;  from  which  cause  its  pulsations  may  be 
very  easily  distinguished  where  the  left  ribs  join  their  car- 
tilages, while  on  the  right  side  of  the  sternum  there  is 
scarcely  ever  a perceptible  pulsation. 

The  Right  Auricle  [Auricula  Dextra,  anterior)  is  an 
oblong  cuboidal  cavity.  It  is  joined  at  its  posterior  supe- 
rior angle  by  the  descending  vena  cava,  and  at  its  posterior 
inferior  angle  by  the  ascending  vena  cava.  The  structure 
of  the  auricle,  between  these  two  points,  seems  to  be  only 
a continuation  of  that  of  the  veins.  These  veins  enter  with 
a direction  slightly  forwards,  so  that  their  columns  of  blood 
are  not  directly  opposed  to  each  other.  In  front  of  this 
continuation  of  the  two  veins,  the  auricle  is  dilated  into  a 
pouch  called  its  sinus;  the  upper  extremity  of  the  latter, 
just  in  front  of  the  descending  cava,  is  elongated  into  a pro- 
cess with  indented  edges,  that  hangs  loose  and  has  some 
general  resemblance  to  the  ear  of  an  animal,  from  which  it 
is  probable  that  the  term  Auricle  has  been  derived. 

The  exterior  surface  of  this  cavity  is  smooth  and  uniform, 
but  its  internal  surface  is  varied  at  several  places.  About 
midway  between  the  orifices  of  the  two  cavae  is  found  a 
transverse  prominence,  the  Tuberculum  Loweri,  which  is 
occasioned  by  the  continuous  structure  of  the  veins  meeting 
at  ail  obtuse  angle.  This  cavity  is  separated  from  the  left 
awriole  only  by  a thin  septum,  which  is  common  to  the 


THE  HEART. 


179 


two  auricles.  On  the  septum,  below  its  middle,  is  a super- 
perficial  circular  depression,  the  Fossa  Oval  is;  it  is  more 
distinct  above  than  below,  and  varies  much  in  its  dimen- 
sions. It  is  surrounded  by  an  elevated  margin  composed 
of  muscular  fibres,  and  called  its  Annulus,  or  the  Isthmus 
of  Vieussens.  The  septum  of  the  auricles  is  thinner  at  the 
fossa  ovalis  than  elsewhere,  and  is  frequently  perforated  by 
one  or  more  foramina:  I once  met,  in  a dissecting  room 
subject,  with  a hole  there,  large  enough  to  transmit  the 
finger.  On  such  occasions,  from  the  valvular  arrangement 
of  the  opening,  it  is  probable  that  the  blood  of  the  two  au- 
ricles is  still  kept  distinct.  The  fossa  ovalis  always  presents 
this  foramen  in  the  fcetal  state. 

Just  below  the  fossa  ovalis  is  found  the  Eustachian  valve, 
consisting  in  a duplication  of  the  lining  membrane  of  the 
auricle.  It  is  crescentic,  but  varies  much  in  its  dimensions 
and  shape.  Its  left  extremity  commences  at  the  left  infe- 
rior margin  of  the  annulus  ovalis;  it  then  extends  itself 
along  the  front  of  the  orifice  of  the  ascending  cava;  where 
the  latter  is  connected  with  the  auricle,  but  never  to  an  ex- 
tent sufficient  to  arrest  the  circulation  there.  Sometimes  it 
is  reticulated  at  its  margin,  and  half  an  inch  wide;  on  other 
occasions,  it  is  scarcely  developed.  Its  loose  edge  looks 
upwards,  and  to  the  right  side.  Its  office  in  the  foetus  is 
clearly,  according  to  the  opinion  of  Sabatier,  to  direct  the 
blood  of  the  ascending  cava  through  the  foramen  ovale. 
In  the  adult  it  may,  on  the  general  principle  of  venous 
valves,  oppose  itself  to  the  introduction  of  refluent  blood 
into  the  ascending  cava;  but  this  office  cannot  be  very  im- 
portant, as  the  valve  is  frequently  scarcely  visible  at  that 
age. 

At  the  lower  part  of  the  right  auricle,  just  to  the  left  of 
the  Eustachian  valve  and  very  near  it,  is  the  orifice  of  the 
large  coronary  vein  of  the  heart;  it  is  protected  by  a small 
semilunar  valve,  ( Valvula  Thebesii,)  formed  also  by  a du- 
plication of  the  lining  membrane  of  the  auricle.  This  ori- 
fice will  admit  a quill  of  common  size  very  readily. 

Betvveen  the  right  auricle  and  ventricle  is  a round  hole.. 


180 


CIKCULA'i'ORT  SYSTEM. 


of  more  than  an  inch  in  diameter,  for  the  passage  of  the 
blood;  it  is  the  Ostium  Venosum.  Its  margin,  on  the  au- 
ricular side,  is  smooth  and  rounded. 

The  parietes  of  the  right  auricle  are  formed  by  muscular 
fibres.  On  the  sinus  these  fibres  are  collected  into  small 
transverse  fasciculi,  called  Musculi  Pectinati,  from  their  re- 
sembling the  teeth  of  a comb.  These  fasciculi,  though 
slightly  united  by  other  fibres,  yet  leave  between  them 
deep  interstices,  by  which  the  external  and  the  internal 
membrane  of  the  heart  come  into  contact.  The  pari- 
etes of  the  auricle  are  muscular,  and  about  one  line  in 
thickness.  Its  muscular  structure  is  continued,  for  a short 
distance,  on  the  two  venae  cavae.  There  are  several  ori- 
fices of  small  veins  on  the  internal  surface  of  this  cavity, 
and  in  greater  abundance  around  the  fossa  ovalis;  they  be- 
long to  the  system  of  coronary  vessels,  and  are  the  forami- 
na Thebesii. 

The  Right  Ventricle  {Ventriculus  Dexter^  anterior.) 
The  general  form  of  this  cavity,  which  receives  the  blood 
from  the  right  auricle,  is  that  of  a triangular  pyramid,  in- 
clined somewhat  backwards,  and  having  its  base  down- 
wards. It  forms  the  greater  part  of  the  anterior  surface  of 
the  heart,  and  is  about  three  lines  in  thickness.  It  is 
bounded  on  its  posterior  face  by  the  left  ventricle,  from 
which  it  is  completely  separated  by  a thick  septum. 

The  internal  surface  of  this  cavity  is  covered  by  muscu- 
lar fasciculi  of  very  irregular  shapes  and  dimensions,  de- 
signated under  the  term  of  ColumnEe  Carneas;  some  of  the 
latter  go  from  one  side  to  the  other;  others  contribute  to  the 
mechanism  of  the  valvular  apparatus  between  it  and  the 
right  auricle;  but  the  greater  portion  is  employed  in  form- 
ing a complicated  reticular  texture  over  the  internal  face  of 
the  ventricle.  Those  connected  with  the  valves  vary  from 
four  to  eight  in  number,  they  are  rounded,  of  different 
lengths  and  sizes,  and  detach  from  their  projecting  extre- 
mity several  small  rounded  tendinous  chords,  {chordse  ten- 
dinex,)  which  are  inserted  into  the  floating  edge  of  the 


THE  HEART. 


ISl 


valve.  These  chords  sometimes  form  an  intertexture  among 
themselves. 

The  Valve,  between  the  ventricle  and  the  auricle,  con- 
sists in  a duplicature  of  the  lining  membrane  of  the  ventri- 
cle, arising  uninterruptedly  from  around  the  ostium  veno- 
sum,  at  the  left  margin;  which  is  there  somewhat  tendinous. 
This  valve  is  called  the  Tricuspid,  ( Valvula  tricuspis,  tri- 
glochis,)  because  its  loose  margin  is  divided  into  three 
points  or  processes.  One  of  these  points,  which  is  at  the 
anterior  external  margin  of  the  orifice,  is  much  larger  than 
the  other  two;  and  more  distinct  in  its  boundaries.  The 
edges  of  these  processes  form  a sort  of  reticulated  work 
along  with  the  adjoining  ends  of  the  tendinous  chords; 
by  this  arrangement  they  are  always  kept  expanded,  and  in 
the  cavity  of  the  ventricle. 

The  opening  for  the  pulmonary  artery  is  placed  above 
the  ostium  venosum;  at  this  point  the  cavity  of  the  ventri- 
cle, instead  of  being  reticulated,  is  made  smooth,  for  the 
more  ready  transmission  of  blood.  The  orifice  of  the  pul- 
monary artery  is  round,  and  about  twelve  lines  in  diameter; 
it  is  furnished  with  three  valves,  called  from  their  shape 
Semilunar  or  Sigmoid.  Each  valve  is  a semicircular  plane, 
formed  from  the  lining  membrane  of  the  artery,  and  at- 
tached to  the  latter  by  its  semi-circumference.  The  dia- 
meter of  the  plane  is  loose,  and,  instead  of  being  straight, 
has  each  semi-diameter  of  a curved  or  festooned  shape;  in 
the  centre  of  its  edge  is  a small  cartilaginous  body,  the  Cor- 
pusculum  Aurantii,  which,  when  the  valve  is  thrown  down 
by  the  reaction  of  the  artery,  comes  in  contact  with  the 
corresponding  bodies  of  the  other  valves,  so  that  they  serve 
as  mutual  abutments.  Between  the  outer  face  of  each 
valve  and  the  artery  there  is  a pouch,  attended  with  a slight 
dilatation  of  the  artery,  and  called  the  Sinus  of  Valsalva. 
Between  the  coats  of  each  valve  there  is  an  additional 
fibrous  substance,  for  the  purpose  of  strengthening  it. 

The  Pulmonary  Artery,  immediately  after  its  origin, 
goes  upwards  and  backwards  to  the  under  part  of  the  cur- 


IS2  CIRCULATORY  SYSTEM. 

vature  of  the  aorta,  and  there  divides  into  two  trunks,  one 
for  each  lung.  These  trunks  separate  widely,  and  from 
the  middle  of  their  fork  proceeds  a ligamentous  substance, 
the  remains  of  the  Ductus  Arteriosus  of  the  foetus,  to  the 
aorta  posteriorly  to  the  origin  of  the  left  subclavian  artery. 
The  right  pulmonary  artery  is  both  longer  and  larger  than 
the  left,  and  passing  transversely  behind  the  aorta  and  the 
descending  cava,  then  penetrates  the  substance  of  the  lung, 
to  be  distributed,  as  mentioned.  The  left  pulmonary  artery 
passes  to  the  lung  in  front  of  the  descending  aorta.  Though 
the  pulmonary  artery  is  quite  as  large  as  the  aorta,  its  pa- 
rietcs  are  thinner. 

The  left  Auricle  [Jluricxda  Sinistra,  posterior)  in  the 
natural  situation  of  the  heart,  is  concealed  by  the  right  au- 
ricle and  the  ventricles.  Its  figure  is  more  regularly  quad- 
rangular, or  square,  than  that  of  the  right,  and  into  each  of 
its  angles  is  introduced  a pulmonary  vein,  there  being  two 
on  each  side.  Sometimes,  however,  the  latter  join  together 
previously,  so  that  the  two  have  but  a common  orifice.  Its 
tip,  or  ear-like  portion,  is  situated  at  the  left  side  of  the 
pulmonaiy  artery,  and  is  longer,  narrower,  more  crooked, 
and  more  notched  at  its  margins  than  the  corresponding 
portion  of  the  right  auricle. 

The  parietes  of  this  cavity  are  muscular,  and  somewhat 
thicker  than  those  of  the  right;  they  are  smooth  and  uni- 
form, both  externally  and  internally,  with  the  exception  of 
its  appendix  or  ear-like  portion,  in  which  the  musculi  pec- 
tinati  prevail.  The  term  sinus  venosus  or  sinus  pulmona- 
lis  of  anatomists;  only  means  that  part  of  the  cavity  into 
which  the  pulmonary  veins  empty.  The  septum  between 
the  auricles,  when  viewed  on  this  side,  has  the  place  of  the 
fos^a  ovalis  marked  out  principally  by  its  diaphanous  con- 
dition. Occasionally  there  is  some  appearance  of  the  valve 
which  once  existed  there. 

At  the  inferior  part  of  the  anterior  side  of  this  cavity  is 
found  the  opening  between  it  and  the  left  ventricle,  also 
called  Ostium  Venosum;  it  is  circular,  and  rather  more  than 


THE  HEART. 


1S3 


an  inch  in  diameter,  resembling  strongly  the  corresponding 
orifice  of  the  right  side  of  the  heart. 

The  Left  Ventricle  ( Ventriculus  Sinister,  posterior)  in 
the  shape  of  its  cavity  resembles  a long  ovoidal  or  conical 
body.  Its  parietes  are  generally  three  times  as  thick  as 
those  of  the  right  ventricle,  amounting  to  about  eight  lines; 
it  is  thicker,  however,  at  its  inferior  than  at  its  superior 
part,  as  it  gradually  decreases  in  approaching  the  aorta. 

Its  internal  surface  is  arranged  on  the  same  principle  with 
that  of  the  right  ventricle,  being  roughened  by  the  presence 
of  numerous  flesh)'"  columns  {Columnse  Carnese)  some  of 
which  are  connected  with  the  valvular  apparatus  between  it 
and  the  left  auricle,  others  form  an  intricate  reticular  tex- 
ture on  its  sides,  and  a few  pass  from  one  side  to  the  other. 
As  this  surface  approaches  the  orifice  of  the  aorta,  it  becomes 
smooth,  so  that  no  impediment  may  be  afforded  to  the  pas- 
sage of  the  blood. 

The  Ostium  Venosum,  on  the  side  of  this  cavity,  has  its 
margin  looking  tendinous,  and  furnished  with  a duplicature 
of  the  lining  membrane  that  surrounds  it.  This  duplication, 
by  being  severed  on  its  loose  edge  into  two  divisions,  obtains 
the  name  of  Mitral  Valve  ( Valvula  Mitralis.)  Its  margin 
is  secured  from  being  pushed  into  the  left  auricle  by  several 
chordae  tendineae,  which  are  attached  by  their  other  extremi- 
ties to  four  or  five  columnae  carneae  projecting  from  the  sur- 
face of  the  ventricle.  The  whole  internal  arrangement  of 
this  cavity  indicates  a great  increase  of  strength  over  that 
of  the  right  side;  in  the  robustness  of  its  fleshy  columns,  the 
number  and  size  of  its  tendinous  chords,  and  the  greater 
thickness  of  its  valve.  The  upper  division  of  the  mitral 
valve  is  placed  immediately  below  the  orifice  of  the  aorta, 
and  is  considerably  broader  than  the  other,  so  that  when  it 
opens  to  admit  blood  it  is  in  some  measure  thrown  over  the 
aortic  orifice.  There  is  less  of  an  intertexture  among  the 
tendinous  chords  here  than  on  the  right  side  of'  the  heart; 
they  cluster  more,  and,  owing  to  the  breadth  of  the  extremi- 
ties of  the  fleshy  columns,  are  more  parallel. 


184 


CIRCULATOBY  SYSTEM. 


The  Septum  of  the  Ventricles  is  of  considerable  thickness, 
being  formed  almost  exclusively  by  the  continuation  of  the 
fibres  of  the  left  ventricle.  Where  the  large  columnse  ear- 
ner elevate  themselves  on  its  surface,  its  thickness  is  in- 
creased. Its  shape  is  somewhat  triangular.  It  forms  a 
round  projection  into  the  right  ventricle,  while  its  other  sur- 
face, which  presents  to  the  left,  is  concave  to  the  same  de- 
gree. It  is  rather  thinner  as  is  approaches  the  auricular 
septum  than  elsewhere.  Its  fibres  near  the  apex  are  less 
closely  connected  to  each  other. 

The  Orifice  of  the  Aorta  is  furnished  with  three  semi- 
lunar Valves,  which,  in  the  mode  of  their  arrangement  cor- 
respond precisely  with  those  of  the  pulmonary  artery. 
They  are  however  thicker,  and  the  Corpuscula  Aurantii 
are  larger.  The  Sinuses  of  Valsalva,  attended  with  a slight 
dilatation  of  the  artery,  exist  in  the  same  way.  Just  be- 
yond the  margins  of  the  right  and  of  the  left  valves  are  ob- 
served the  orifices  of  the  two  coronary  arteries.  The  ori- 
fice of  the  aorta  is  somewhat  tendinous,  which  marks  out 
the  distinction  of  structure  between  it  and  the  ventricle. 

Of  the  Pericardium. 

The  heart,  as  stated,  is  surrounded  by  its  proper  capsule, 
called  the  Pericardium,  which  separates  it  from  the  adjoin- 
ing parts,  and  sustains  it  in  its  dilatations.  ' The  pericardium 
is  covered  on  its  sides  by  the  pleurae,  and  reposes  on  the 
tendinous  centre  of  the  diaphragm,  to  which  it  adheres  by 
close  compact  cellular  substance,  particularly  at  its  periphery. 
When  the  latter  attachment  is  cut  through,  a separation  of 
the  remainder  is  easily  effected.  Behind,  the  pericardium 
is  opposed  to  the  bronchiae  and  the  oesophagus. 

The  pericardium  does  not  adhere  to  the  heart,  except  at 
the  base  of  the  latter;  it  is,  therefore,  a loose  capsule  in,  by 
far,  the  greater  part  of  its  extent.  It  not  only  surrounds 
the  heart,  but  also  the  roots  of  the  large  arteries  and  veins 
connected  with  it.  Thus  it  includes  the  aorta,  as  high  up 
as  the  great  vessels  proceeding  from  its  arch;  from  the  lat- 


THE  HEART. 


185 


ter,  it  passes  to  the  trunk  of  the  pulmonary  arter}’-,  and  also 
includes  it,  causing  the  aorta  and  the  pulmonary  artery  to 
lie  close  together.  The  posterior  face  of  these  vessels  is  not 
covered  so  high  up  as  the  anterior  face.  The  pericardium 
also  invests  the  descending  vena  cava  for  an  inch  above  its 
junction  with  the  right  auricle;  it  likewise  invests  the 
trunks  of  the  pulmonary  veins,  and  the  ascending  cava  as 
it  rises  above  the  diaphragm.  The  pouches  which  it  forms 
at  the  base  of  the  heart,  in  passing  from  one  of  these  ves- 
sels to  another,  are  the  cornua  of  some  anatomists.  It  can- 
not be  considered  as  pierced  for  the  passage  of  these  ves- 
sels, but  is  lost  insensibly  on  their  parietes;  being  continued 
into  the  cellular  covering  of  the  arteries,  in  accompanying 
them  to  a great  distance.  * 

The  pericardium  is  a double  membrane,  or  consists  of  two 
layers,  an  internal  and  an  external  one.  The  external  mem- 
brane, to  which  the  preceding  description  is  especially  ap- 
plicable, resembles  strongly  the  dura  mater,  but  is  thinner; 
it  is  therefore  white,  semitransparent,  fibrous  and  inelastic. 
Its  thickness  is  greater  on  the  sides,  than  below  where  it 
rests  upon  the  diaphragm,  or  above,  where  it  goes  along  the 
great  vessels;  its  fibres  are  irregularly  disposed  and  inter- 
woven, but  many  may  be  traced  longitudinally. 

The  internal  membrane  lines  the  external,  and  gives  the 
polish  to  its  cardiac  surface;  it  is  then  conducted  along  the 
surface  of  the  several  vessels  that  have  been  mentioned,  to 
the  heart,  over  the  whole  of  which  it  is  spread,  and  adheres 
to  it  by  cellular  substance,  frequently  containing  much  adi- 
pose matter;  it  also  causes  the  heart  to  have  a smooth 
shining  surface.  This  is  a very  delicate  thin  serous  mem- 
brane; and  secretes  a fluid,  transparent  and  somewhat  unc- 
tuous, like  that  of  the  joints,  but  not  so  consistent;  which 
lubricates  the  surface  of  the  heart  and  permits  it  to  play 
freely  within  its  pericardium.  This  fluid,  in  a natural  state, 
seldom  exceeds  a tea-spoonful  though  two  ounces  or  a lit- 

* Sabatier  Trait.  d’Anat.  vol.  ii.  p.  284. 

Voi..  II. — 24 


CIRCULATORV  SYSTEM. 


18(? 

tie  more  are  not  considered  sufficient  evidence  of  a patholo- 
gical state;  its  augmentation  constitutes  a dropsy. 

After  death,  we  find  the  pericardium  lying  loosely  upon 
the  heart,  from  the  vacuity,  and  consequently  diminished 
bulk  of  the  latter;  but  while  the  circulation  is  going  on 
the  heart  fills  and  distends  it.  A striking  resemblance  is 
observable  between  the  condition  of  the  pericardium  and 
the  moveable  articulations.  Its  external  membrane  cor- 
responds with  the  strong  fibrous  capsule  that  passes  from 
one  bone  to  the  other;  while  the  internal  is  the  synovial 
bag,  which  scarcely  assists  in  the  strength  of  the  apparatus, 
but  secretes  a fluid  to  render  motion  easy.  Several  in- 
stances are  on  record  of  a total  absence  of  pericardium. 

Of  the  Texture  of  the  Heart. 

The  Heart,  with  the  exception  of  the  membrane  which 
lines  its  cavities,  and  of  the  serous  lamina  of  pericardium 
which  covers  its  surface,  consists  entirely  of  muscular 
fibres. 

The  sides  of  the  auricles,  as  stated,  are  much  thinner 
than  those  of  the  ventricles.  In  the  right  auricle,  the  stra- 
tum of  muscular  fibres  is  uniform  in  its  venous  portion,  but 
on  the  sinus  is  arranged  into  the  parallel  fasciculi  called 
the  Musculi  Pectinati:  a circular  fasciculus  surrounds  the 
orifice  of  the  descending  cava.  In  the  left  auricle,  the  stra- 
tum of  muscular  fibres  forms  a uniform  layer,  and  is  also 
thicker  than  on  the  i-ight  side.  These  fasciculi  commence 
on  the  pulmonary  veins  and  run  transversely  across  the  au- 
ricle, with  the  exception  of  the  more  deeply  seated,  which 
are  irregular,  and  crossed  upon  each  other.  The  septum 
of  the  auricles  is  also  formed  by  a muscular  stratum. 

In  the  ventricles,  the  superficial  fasciculi  observe  a spiral 
course,  and  many  of  those  belonging  to  the  left  ventricle 
may  be  traced  over  the  right;  as  the  fibres  are  more  deeply 
situated,  they  become  shorter  and  more  interwoven.  In 
the  septum,  between  the  ventricles,  the  fibres  of  the  two  ca- 
vities are  much  interlocked;  but,  with  some  trouble,  may 


THE  HEART. 


187 


be  separated.  The  fibres  of  the  columrue  carnas  are  too  ir- 
regular in  their  course  to  admit  even  of  a general  descrip- 
tion. 

Of  the  Blood  Vessels  of  the  Heart. 

The  Heart  is  furnished  with  both  arteries  and  veins, 
which  belong  to  its  nutritious  system. 

The  arteries  called  Coronary  arise,  as  observed,  from  the 
trunk  of  the  aorta,  somewhat  above  the  margins  of  the  se- 
milunar valves,  so  that  when  the  latter  are  applied  against 
the  aorta,  the  orifices  of  these  arteries  are  still  visible. 

The  Right  Coronary  Artery  begins  above  the  anterior 
valve,  and  passes  to  the  right,  beneath  the  pulmonary  ar- 
tery; it  then  shows  itself  in  the  upper  part  of  the  fissure, 
between  the  right  auricle  and  right  ventricle,  and  follows 
the  course  of  this  fissure  to  the  flat  side  of  the  heart.  It 
detaches,  as  it  goes  along,  several  small  branches,  which 
come  off  at  right  angles  from  it.  One  set  of  these  branches 
is  distributed  upon  the  right  ventricle,  and  another  set  upon 
the  right  auricle.  Small  branches  are  also  sent  from  it  to 
the  root  of  the  pulmonary  artery,  and  to  that  of  the  aorta. 

The  Left  Coronary  Artery  begins  above  the  left  semilu- 
nar valve.  While  its  root  is  still  obscured  by  the  pulmo- 
nary artery,  it  divides  into  two  principal  branches,  of.^which 
the  anterior  runs  in  the  fissure  on  the  upper  part  of  the  sep- 
tum of  the  ventricles  to  the  apex  of  the  heart,  and  in  this 
course  distributes  branches  to  the  x'ight  and  left  ventri- 
cles; those  to  the  right  anastomose  with  the  branches  of 
the  right  coronary  artery,  which  go  to  the  same  ventricle. 
The  other  branch  goes  along  the  groove,  on  the  septum, 
between  the  left  auricle  and  left  ventricle,  and  reaches  the 
under  surface  of  the  heart;  and  in  this  course  distributes 
many  branches  to  the  left  auricle  and  left  ventricle,  both  on 
their  upper  and  under  surfaces.  It  anastomoses,  freely  with 
the  branches  of  the  trunk  that  I'uns  along  the  upper  part 
of  the  septum. 


ISS 


ClKCULATOllir  SysTEM. 


In  consequence  of  the  frequency  of  the  anastomoses  be- 
tween the  two  coronary  arteries,  injecting  matter  thrown 
into  one  very  readily  finds  its  way  into  the  other. 

The  Coronary  Veins  receive  the  blood,  which  is  distri- 
buted by  the  coronary  arteries  through  the  substance  of  the 
heart. 

The  Gi’eat  Coronary  Vein  {Vena  Coronaria  Maxima 
Cordis)  is  formed  by  the  union  of  several  trunks,  which 
run  from  the  apex  towards  the  base  of  the  heart.  One  of 
them  begins  at  the  apex,  goes  along  the  superior  fissure  of 
the  septum  of  the  ventricles,  and  then  winds  to  the  left  side, 
between  the  left  auricle  and  the  left  ventricle;  while  in 
the  latter  position,  it  is  joined  by  several  trunks  coming 
from  the  left  ventricle  and  the  left  auricle;  it  finally  emp- 
ties into  the  lower  part  of  the  right  auricle,  just  in  front,  as 
mentioned,  of  the  orifice  of  the  ascending  cava;  being  there 
covered  by  its  own  valve. 

The  Lesser  Coronary  Vein  ( Vena  Coron.  Minor  Cordis) 
lies  in  the  inferior  fissure  of  the  septum  of  the  ventricles. 
It  begins  at  the  apex,  and,  going  backwards,  collects  the 
blood  from  the  flat  surface  of  the  heart,  principally  on  the 
right  ventricle.  It  discharges  into  the  great  coronary  vein, 
just  before  the  latter  terminates  in  the  auricle. 

Besides  the  preceding  veins,  some  of  a smaller  size  exist 
on  the  right  ventricle,  and  about  the  root  of  the  aorta  and 
pulmonary  artery,  and  empty  by  several  orifices  into  the 
right  auricle.  There  are  also  some  veins  of  a still  smaller 
size,  which  open  into  all  the  cavities  of  the  heart  by  little 
orifices,  called  the  foramina  of  Thebesius;  by  Mr.  Aber- 
nethy  they  are  considered  as  being  larger  when  the  lungs 
are  diseased.  * 

The  Nerves  of  the  Heart  come  principally  from  the  cer- 
vical ganglions  of  the  sympathetic,  and  follow  the  course 

* London  Philosophical  Transactions,  1798. 


THE  HEART. 


189 


of  the  coronary  arteries.  It  has  been  doubted  whether  these 
nerves  are  actually  distributed  in  the  substance  of  the  heart, 
from  the  presumption,  that  as  they  cannot  be  traced  beyond 
the  third  order  of  branches  of  the  coronary  arteries,  they 
are  limited  to  them.  But,  as  the  ramifications  of  the  sym- 
pathetic are  bestowed  exclusively  upon  the  branches  of  the 
circulatory  system,  Meckel  has  very  properly  suggested, 
that  the  heart  being  also  supplied  with  nerves  from  the  same 
source,  it  follows  that  there  can  be  no  departure  from  the 
general  rule,  as  the  heart  is  nothing  more  than  the  fibrous 
portion  of  the  blood  vessels  more  completely  developed. 

While  the  circulation  continues,  as  both  auricles  contract 
at  the  same  instant,  whereby  the  blood  is  thrown  into  the 
ventricles;  and  as  immediately  afterwards  the  ventricles 
Contract  simultaneously  also,  whereby  the  blood  is  forced 
into  the  aorta  and  the  pulmonary  artery;  so  it  is  the  con- 
traction of  the  ventricles  which  causes  the^  heart  to  strike 
against  the  parietes  of  the  thorax.  For,  as  was  first  pointed 
out  by  Dr.  W.  Hunter,  the  blood  which  is  forced  through 
the  large  arteries,  by  extending  them  diminishes  their  cur- 
vature, or  brings  them  more  into  a straight  line,  in  which 
efibrt  the  heart  bounds  up  from  the  tendinous  centre  of  the 
diaphragm.  The  filling  of  the  auricles,  while  this  is  going 
on,  also  assists  in  protruding  the  heart  forwards.  The 
French  anatomists  assert,  that  during  the  contraction  of  the 
ventricles,  their  extremity  is  elevated  or  bent  upwards  on 
the  body  of  the  heart,  which  will  also  increase  the  momen- 
tum of  the  stroke  against  the  thorax. 


190 


CIRCULATORY  SYSTEM. 


CHAPTER  II. 

OP  THE  ARTERIES. 

SECT.  I. THE  AORTA  AND  THE  BRANCHES  PROM  ITS 

CURVATURE. 

The  Aorta  is  the  trunk  of  the  arterial  system.  Having 
arisen  from  the  superior  posterior  end  of  the  left  ventricle, 
its  root  passes  beneath  the  pulmonary  artery,  and  is  entirely 
concealed  in  front  by  it.  Keeping  to  the  right  it  emerges 
from  the  base  of  the  heart,  between  the  right  auricle  and 
the  trunk  of  the  pulmonary  artery,  being  bounded  on  the 
right  side  by  the  Descending  Cava.  Continuing  its  ascent, 
it  forms  a curvature  with  the  convexity  upwards,  and  the 
summit  of  which  rises  to  within  eight  or  twelve  lines  of  the 
superior  edge  of  the  sternum.  This  curvature  is  in  front  of 
the  third  and  fourth  dorsal  vertebra?,  and  its  direction  is 
nearly  marked  out  by  a line  drawn  from  the  anterior  extre- 
mity of  the  third  right  rib,  to  the  posterior  end  or  tubercle 
of  the  third  one  on  the  left  side.  In  this  course,  therefore, 
the  aorta  passes  over  the  right  pulmonary  artery,  across  the 
left  bronchia,  and  applies  itself  to  the  left  side  of  the  spine, 
about  the  third  or  fourth  dorsal  vertebra.  It  is  this  curva- 
ture which  obtains  the  name  of  the  Arch  of  the  Aorta 
cus  Aortse. ) 

Near  its  origin,  where  the  aorta  is  still  within  the  peri- 
cardium, it  has  very  commonly,  especially  in  persons  ad- 
vanced in  age,  a dilatation,  which  is  called  the  great  sinus, 
to  distinguish  it  from  the  lesser  sinuses,  or  those  of  Val-  I 
salva.  The  ascending  portion  of  the  arch  is  to  the  right  of 
the  vertebral  column,  the  descending  portion  to  the  left,  and 
the  middle  or  horizontal  part  goes  in  front  of  the  trachea.  j 

The  Aorta,  in  its  descent  down  the  thorax,  is  placed  in  ' 

the  posterior  mediastinum,  and  is  covered  on  one  side  by  j 
the  left  pleura,  while  the  other  side  is  in  contact  with  the 


BRANCHES  EEOM  THE  ARCH  OE  THE  AORTA. 


191 


left  surface  of  the  bodies  of  the  dorsal  vertebrae.  At  the 
lower  part  of  the  thorax  it  inclines  towards  the  middle  line 
of  the  vertebras,  in  order  to  reach  the  hiatus  aorticus  of  the 
Diaphragm,  through  which  it  penetrates  to  the  abdomen. 
In  the  abdomen  it  descends  in  front  of  the  lumbar  vertebrae, 
somewhat  inclined  to  their  left  side;  and  at  the  interverte- 
bral space  between  the  fourth  and  fifth  vertebrae  of  the  loins, 
or  somewhat  above  it,  it  ceases,  by  being  divided  into  two 
large  trunks,  the  Primitive  Iliacs;  one  for  each  lower  extre- 
mity, and  the  corresponding  side  of  the  Pelvis. 

In  this  course  of  the  aorta  from  the  heart  to  the  loins,  it 
first  gives  off  the  branches  which  supply  the  head  and  the 
superior  extremities;  then,  those  which  supply  the  sides  of 
the  thorax;  afterwards,  in  the  abdomen,  it  detaches  the 
trunks  which  supply  the  viscera  and  the  sides  of  the  latter 
cavity. 

The  Coronary  Arteries  are,  strictly  speaking,  the  first 
branches  of  the  aorta,  but  as  they  belong  especially  to  the 
heart,  their  description  is  associated  with  it.  In  all  the 
space  between  them  and  the  superior  convexity  of  the  aortic 
arch  no  branches  are  given  off;  but  as  the  aorta  is  crossing 
the  trachea  three  considerable  trunks  arise  from  it,  which 
are  distributed  upon  the  head  and  the  upper  extremities 
principally.  They  are,  the  Arteria  Innominata,  the  Left 
Primitive  Carotid,  and  the  Left  Subclavian. 

The  Arteria  Innominata  is  first  in  its  origin,  in  ascend- 
ing from  left  to  right  in  front  of  the  trachea,  and  behind  the 
transverse  vein,  it  crosses  the  trachea  very  obliquely;  is 
from  an  inch  to  an  inch  and  a half,  and  sometimes,  though 
rarely,  two  inches  long,  when  it  divides  into  the  right  sub- 
clavian and  the  right  primitive  carotid.  The  left  primitive 
carotid  arises  from  the  aorta,  close  upon  the  left  border  of 
the  innominata,  frequently,  indeed,  from  a part  of  it.  The 
left  subclavian,  though  at  its  origin  near  the  left  carotid, 
generally  leaves  a distinct  interval  of  one,  two,  or  three 
lines.  The  relative  situation  of  these  trunks  is  particularly 


192 


CIKCULATORT  SYSTEM. 


alluded  to  in  the  account  of  the  superior  mediastinum.  The 
two  last  are  of  course  longer  that  the  corresponding  trunks 
of  the  right  side,  by  the  whole  length  of  the  arteria  inno- 
minata.  With  the  exceptions  connected  with  their  mode 
of  origin,  the  arterial  trunks  of  the  two  sides  are  exactly 
alike,  and  have  the  same  mode  of  distribution. 

The  Common  Carotid  Artery  {Carotis  Primitiva)  being 
a branch  of  the  innominata  on  the  right  side,  and  of  the 
aorta  on  the  left,  goes  up  the  neck  to  terminate  just  below 
the  cornu  of  the  os  hyoides.  In  the  early  part  of  its  course 
the  right  one  is  more  inclined  outwardly  than  the  left,  owing 
to  its  origin  from  the  arteria  innominata  in  front  of,  and  to 
the  right  side  of  the  trachea,  whereas  the  left  ascends  almost 
vertically. 

At  the  lower  part  of  the  neck,  just  above  the  sternum  and 
the  clavicle,  the  carotid  is  covered  by  the  sterno-hyoid  and 
thyroid  muscles,  and  by  the  sternal  portion  of  the  sterno- 
cleido-mastoid.  It  is  crossed  obliquely  on  a line  with  the 
lower  part  of  the  thyroid  cartilage  or  of  the  larynx,  by  the 
omo-hyoid  muscle.  It  lies  at  the  side  of  the  thyroid  gland, 
the  trachea,  the  larynx,  the  oesophagus,  and  pharynx,  in 
front  of  the  transverse  processes  of  the  cervical  vertebras,' 
and  the  longus  colli  muscle;  having  on  its  outer  margin,  but 
somewhat  in  front,,  the  internal  jugular  vein  and  the  pneu- 
mogastric  nerve  enclosed  in  the  same  sheath,  and  the  sym- 
pathetic nerve  behind.  At  the  side  of  the  larynx  the  ca- 
rotid is  very  suiaerficial,  and  with  the  exception  of  being 
crossed  by  the  omo-hyoideus  muscle,  it  is  only  covered  by 
the  platysma  myoides  and  the  integuments. 

The  Carotid  having  got  as  high  as  the  space  between  the 
os  hyoides  and  the  thyroid  cartilage,  but  varying  slightly 
in  different  subjects,  there  divides  into  two  large  trunks,  the 
Internal  Carotid,  which  goes  to'jthe  brain  and  to  the  eye, 
and  the  External  Carotid,  which  is  principally  distributed 
upon  the  more  superficial  parts  of  the  head  and  neck.  The 
first  of  these  trunks  is  placed  behind  the  other,  and  bends 
outwardly  at  its  root:  it  is  generally  the  largest  in  infancy, 


CAROTIDS  AND  THEIR  BRANCHES. 


193 


mi  account  of  the  proportionate  volume  of  the  brain  at  that 
age;  it  is  also  swollen  at  its  root,  so  as  to  form  a sinus  there 
resembling  an  incipient  aneurism.  No  branch,  except  in 
anormal  cases,  is  given  off  from  the  carotid  between  its 
•origin  and  this  bifurcation. 

SECT.  II. OF  THE  CAROTIDS  AND  THEIR  BRANCHES. 

The  Internal  Carotid  {Jirteria  Carotis  Interna)  in  the 
adult  is  smaller  than  the  external,  and  extends  from  the 
larynx  to  the  sella  turcica.  It  ascends  between  the  external 
carotid  and  the  vertebrae  of  the  neck,  being  in  front  of  the 
internal  jugular  vein,  and  having  the  pneumogastric  nerve 
at  its  outer  margin ; as  it  gets  on  a level  with  the  base  of  the 
lower  jaw,  it  is  crossed  externally  by  the  digastric  and  the 
stylo-hyoid  muscles;  it  is  immediately  afterwards  concealed 
in  the  subsequent  part  of  its  ascent  by  the  ramus  of  the 
lower  jaw.  Having  gone  along  the  most  internal  or  deeply 
seated  margin  of  the  parotid  gland  and  the  styloid  process 
of  the  temporal  bone,  at  the  side  of  the  superior  constrictor 
of  the.  pharynx,  it  then  penetrates  into  the  cranium  through 
the  carotid  canal  of  the  temporal  bone. 

It  is  slightly  flexed  between  its  origin  and  the  carotid 
canal;  just  before  it  reaches  the  latter  it  curves  upwards  and 
forwards.  The  first  part  of  its  course  through  the  canal  is 
vertical,  afterwards  it  goes  horizontally  forwards;  and  to 
escape  from  the  canal  it  has  once  more  to  ascend  almost 
vertically,  which  brings  it  to  the  posterior  extremity  of  the 
Sella  Turcica.  On  the  side  of  the  Sella  Turcica  it  asain 
passes  horizontally  forwards  through  the  cavernous  sinus; 
and  at  the  anterior  clinoid  process  it  once  more  ascends, 
and  having  penetrated  the  dura  mater  it  reaches  the  brain. 

In  this  passage  through  the  carotid  canal  it  is  attended  by 
the  upper  extremity  of  the  sympathetic  nerve,  and  gives 
one  or  more  small  branches  to  the  petrous  bone;  it  also 
gives  a few  branches  to  the  dura  mater  and,  to  the  nerves 
about  the  cavernous  sinus.  But  for  the  full  exposition  of 

VoL.  II. —25 


194 


CIKCULATORV  SYSTEM. 


the  distribution  of  the  internal  carotid  see  the  articles  Brain 
and  Eye. 

The  External  Carotid  Artery  {Carotis  Externa)  extends 
from  the  termination  of  the  primitive  carotid,  to  the  neck 
of  the  lower  jaw.  In  the  early  part  of  its  course,  where 
it  is  situated  in  front  of  the  internal  carotid,  and  between 
the  pharynx  and  the  sterno-mastoid  muscle,  it  is  compara- 
tively superficial,  being  only  enveloped  by  its  sheath,  and 
covered  by  the  platysma  myoides  and  the  skin.  Just  above 
this  place  it  is  crossed  externally  by  the  hypoglossal  nerve, 
which  detaches  the  descending  branch  along  the  front  of 
its  sheath  and  of  that  of  the  primitive  carotid.  Somewhat 
above  this  nerve  it  is  also  crossed  externally  by  the  digas- 
tric and  the  stylo-hyoid  muscle,  and  lies  there  on  the  side 
of  the  superior  constrictor  muscle  of  the  pharynx,  near  the 
tonsil  gland.  About  its  middle  it  is  crossed  internally  by 
the  stylo-glossus  and  the  stylo-pharyngeus  muscle;  it  then 
ascends  through  the  substance  of  the  parotid  gland,  be- 
tween the  ramus  of  the  lower  jaw  and  the  ear,  to  its  termi- 
nation. 

Several  very  important  branches  are  given  off  -from  the 
external  carotid;  they  are  as  follow: 

The  Superior  Thyroid  Artery  {Art.  Thyroidea  Supe- 
rior) arises  from  the  external  carotid,  about  a line  above 
its  root,  and  is  distributed  to  the  larynx  and  to  the  thyroid 
gland.  It  goes  at  first  inwards  and  forwards  on  the  side  of 
the  larynx,  being  covered  by  the  omo-hyoideus  muscle,  and 
by  the  platysma  myoides,  it  then  descends  under  the  ster- 
no-thyroideus  to  the  upper  margin  of  the  lobe  of  the  thy- 
roid gland.  In  this  course  it  performs  several  flexuosities, 
of  considerable  variety  in  different  individuals. 

The  Laryngeal  Branch  comes  from  it  near  the  superior 
margin  of  the  thyroid  cartilage;  this  branch  glides  in  be- 
tween the  thyreo-hyoid  muscle  and  the  membrane  of  the 
same  name;  after  a short  course  it  penetrates  the  latter,  and 
is  then  distributed  in  a great  number  of  small  twigs  to  the 


CAROTIDS  AND  THEIR  BRANCHES, 


195 


muscles  and  to  the  lining  membrane  of  the  larynx.  A small 
trunk,  either  from  the  laryngeal  branch,  or  from  the  thy- 
roid artery  itself,  is  spent  upon  the  crico-thyroid  muscle, 
and  traversing  the  front  surface  of  the  middle  crico-thyroid 
ligament  anastomoses  with  its  fellow:  small  twigs  from  this 
branch  penetrate  to  the  interior  of  the  larynx  through  the 
crico-thyroid  ligament.  Sometimes  this  crico-thyroid  ra- 
mus is  superior  in  size  to  the  one  above,  in  which  case  it 
principally  supplies  the  interior  of  the  lar)mx. 

The  Thyroid  Branch  is  the  continuation  of  the  princi- 
pal trunk;  it  penetrates  into  the  substance  of  the  thyroid 
gland,  and  divides  into  two  ramuscles,  one  of  which  goes 
along  the  posterior  face  of  the  lobe  of  the  gland,  and  anas- 
tomoses with  the  inferior  thyroid;  the  other  goes  along  the 
upper  margin  of  the  gland,  and  anastomoses  with  its  con- 
gener of  the  opposite  side.  The  thyroidal  artery  is  split 
up  into  a great  many  branches  in  the  substance  of  the  gland, 
it  also  sends  small  branches  to  the  pharynx,  oesophagus,  and 
the  little  muscles  on  the  front  of  the  neck. 

The  Lingual  Artery  {Art.  Lingualis)  comes  from  the 
external  carotid  at  the  distance  of  from  six  to  twelve  lines 
above  the  superior  thyroid,  and  goes  to  the  tongue.  It  is 
concealed  in  the  early  part  of  its  course  by  the  digastric 
and  the  stylo-hyoid  muscles;  it  then  penetrates  the  hyo- 
glossus  muscle  just  above  the  cornu  of  the  os  hyoides,  or 
goes  between  it  and  the  middle  constrictor  of  the  pharynx; 
it  then  ascends  between  the  hyo-glossus  and  the  genio-hyo- 
glossus  muscle;  advancing  forwards,  it  is  placed  between 
the  latter  and  the  sublingual  gland,  and  finally  reaches  the 
tip  of  the  tongue. 

The  lingual  artery  sends  off  the  following  branches.  At 
the  root  of  the. tongue  one  or  more  trunks  arise  from  it 
{Dorsates  Linguae)  which  go  to  the  base  of  this  organ, 
the  tonsils,  the  palate,  and  the  epiglottis.  A little  fur- 
ther on,  this  artery  detaches  another  branch  {Ramus  Sub- 
lingualis) which  advancing  between  the  mylo-hyoid  and 
the  genio-hyo-glossus  muscles,  and  above  the  sublingual 
gland,  detaches  a great  many  ramifications  to  these  parts 


196 


CIKCULATOKY  SYSTEM. 


and  to  the  lining  membrane  of  tlie  mouth;  it  is  sometimes 
a branch  of  the  facial.  The  Ramus  Raninus,  is  the  conti- 
nuation of  the  lingual;  it  advances  between  the  lingualis 
and  the  genio-hyo-glossus  muscles,  to  the  tip  of  the  tongue, 
distributing  continually  its  twigs  on  each  margin,  and  ends 
there  by  anastomosing  with  the  corresponding  arteiy  of  the 
other  side. 

The  Facial  Artery  {Jlrteria  Facialis,  Maxillaris  Ex- 
terna) arises  from  the  external  carotid,  two  or  three  lines 
above  the  lingual,  and  is  spent  principally  on  the  side  of 
the  face  below  the  eye.  It  is  of  considerable  size,  and  very 
tortuous;  its  root  is  concealed  by  the  stylo-hyoid  and  the 
digastric  muscles,  and  it  is  traversed  externally  by  the  hy- 
poglossal nerve.  It  goes  forwards  within  the  angle  of  the 
lower  jaw  and  above  the  submaxillary  gland,  but  very  much 
connected  with  it:  it  then  mounts  over  the  base  of  the  max- 
illa inferior,  at  the  anterior  margin  of  the  masseter  muscle, 
and  afterwards  shapes  its  course,  in  a serpentine  manner, 
to  the  internal  canthus  of  the  eye,  passing  between  the 
muscles  and  the  integuments  of  the  face.  In  this  course 
the  facial  artery  sends  off  the  following  branches. 

As  it  passes  by  the  submaxillary  gland  it  sends  several 
twigs  to  it:  previously  it  also  sends  several  little  branches 
to  the  contiguous  muscles,  as  the  internal  pterygoid,  di- 
gastric, and  so  on,  but  they  are  too  small  to  be  of  much  con- 
sequence. 

The  Submental  branch  arises,  then,  on  a level  with  the 
base  of  the  lower  jaw;  it  advances  forwards  under  the  ori- 
gin of  the  mylo-hyoideus,  and  above  the  anterior  belly  of 
the  digastricus.  It  sends  several  ramuscles  to  these  mus- 
cles, some  of  which  anastomose  with  the  ranine  artery; 
behind  the  symphysis  of  the  jaw  it  anastomoses  with  its 
fellow,  it  then  mounts  over  the  chin,  to  which  and  to  the 
lower  lip  it  is  distributed,  anastomosing  there  with  the  in- 
ferior coronary  artery  of  the  mouth,  and  with  the  inferior 
maxillary  which  comes  out  from  the  anterior  mental  fora- 
men in  the  lower  jaw. 

When  the  facial  artery  has  got  upon  the  face,  it  sends 


CAROTIDS  AND  THEIR  BRANCHES. 


197 


backwards  a small  branch  to  the  lower  part  of  the  masseter 
muscle.  Somewhat  above  this  it  sends  forwards  a branch 
called  the  Inferior  Labial,  which  is  distributed  upon  the  mid- 
dle of  the  chin.  When,  it  gets  on  a level  with  the  corner 
of  the  mouth,  but  sometimes  lower  down,  it  sends  for- 
wards, under  the  depressor  anguli  oris,  the  Inferior  Coro- 
nary Artery,  to  the  lower  lip,  which  frequently  supplies 
the  place  of  the  inferior  labial  entirely;  but  when  the  latter 
is  large  the  coronary  is  small  in  proportion;  a few  lines 
higher  up  the  facial  sends  forwards  a third  branch,  the  Su- 
perior Coronary,  which  goes  to  the  upper  lip.  These  coro- 
nary arteries  ai'e  very  tortuous,  and  are  distributed  by  many 
branches  in  the  substance  of  the  lips:  by  anastomosing  with 
their  congeners  of  the  other  side,  they  surround  the  mouth 
completely.  The  superior  coronary  artery,  as  it  passes 
under  the  nose,  sends  upwards  one  or  more  small  branches 
to  the  integuments  of  its  orifice  and  septum. 

After  this,  the  facial  artery,  in  ascending  towards  the  in- 
ternal canthus  of  the  eye,  sends  a branch  to  the  ala  nasi,  and 
another  to  anastomose  with  the  infra-orbitar  artery.  It 
finally  terminates  at  the  internal  canthus  of  the  eye  by  anas- 
tomosing with  the  branches  of  the  ophthalmic,  which  come 
out  there  u^ion  the  side  of  the  root  of  the  nose.  Several  ra- 
muscules,  which  are  too  small  to  merit  special  description, 
are  given  by  the  facial  to  the  integuments  and  muscles  of 
the  face,  and  to  the  lower  eyelid. 

The  Inferior  Pharyngeal  Artery  {•Art.  Pharyngea  In- 
ferior, ascendens)  is  one  of  the  smallest  of  the  original 
branches  of  the  external  carotid,  and  generally  arises  oppo- 
site to  the  lingual;  but  there  is  much  variety  in  the  latter 
respect,  it  being  sometimes  higher  up  or  lower  down,  and 
not  unfrequently  a branch  of  one  of  the  other  arteries,  in- 
stead of  being  an  original  trunk.  It  ascends  on  the  side  of 
the  pharynx,  between  the  external  and  the  internal  carotid, 
and  is  covered  by  the  st}do-pharyngeus  muscle.  It  is  prin- 
cipally distributed  on  the  constrictor  muscles  of  the  pharynx, 
and  upon  their  lining  membrane.  But  one  of  its  branches, 
called  the  Posterior  Meningeal  Artery,  ascends  through 


19S 


CIRCULATORY  SYSTEM. 


the  jDOsterior  foramen  lacerum  of  the  cranium,  between  the 
jugular  vein  and  the  pneumo-gastric  nerve,  and  is  distri- 
buted on  the  contiguous  dura-mater. 

The  Occipital  Artery  {Jirteria  Occipitalis)  is  a very  con- 
siderable trunk,  which  comes  from  the  external  carotid,  gene- 
rally opposite  to  the  facial,  and  is  spent  upon  the  integu- 
ments, on  the  back  part  of  the  head. 

At  its  root,  it  is  deeply  situated  in  the  side  of  the  neck,  be- 
low the  parotid  gland,  and  has  the  internal  jugular  vein  and 
the  par  vagum  on  its  inside..  It  goes  obliquely  backwards, 
in  ascending  along  the  posterior  belly  of  the  digastricus,  be- 
tween the  transverse  process  of  the  atlas  and  the  mastoid  por- 
tion of  the  temporal  bone,  being  covered  by  the  several  mus- 
cles which  are  inserted  into  the  latter,  as  the  sterno-mastoid, 
the  splenius;  and  the  trachelo-mastoid.  It  is  covered,  for 
some  distance,  by  the  insertion  of  the  splenius  capitis,  and 
becomes  at  length  superficial  at  the  posterior  margin  of  this 
muscle.  The  occipital  artery  is  distributed  as  follows: 

Shortly  after  its  origin,  it  sends  branches  to  the  digastric 
muscle  behind,  to  the  upper  part  of  the  sterno-mastoid  and 
to  the  lymphatic  glands  of  the  upper  part  of  the  neck.  While 
enclosed  by  the  muscles  on  the  back  of  the  neck,  it  also  sends 
branches  to  them,  and  anastomoses  thereby  with  the  vertebral 
artery;  occasionally,  one  of  these  branches  is  of  considerable 
magnitude,  and  has  been  found  descending  very  low  on  the 
back,  between  the  splenius  and  the  coniplexus  muscles.  It 
also  sends  a small  branch  to  the  dura  mater,  through  the 
mastoid  foramen  generally,  but  sometimes  through  the  pos- 
terior foramen  lacerum.  When  the  stylo-mastoid  artery  is 
wanting,  it  also  detaches  a branch  through  the  stylo-mastoid 
foramen  to  the  internal  parts  of  the  ear. 

The  occipital  artery,  having  become  superficial  at  the  in- 
ternal margin  of  the  splenius  on  the  occiput,  ascends  on  the 
latter  bone  towards  the  vertex  in  a tortuous  manner,  sending 
off,  on  each  .side,  many  small  ramifications.  It  ends  by  anas- 
tomosing with  the  posterior  temporal  artery. 

The  Posterior  Auricular  Artery  Jiuricularis  Paste- 


CAROTIDS  AND  THEIR  BRANCHES.  199 

rior)  arises  a little  above  the  last,  at  the  lower  edge  of  the  pa- 
rotid gland,  from  the  external  carotid,  and  is  one  of  its  small- 
est branches.  It  ascends  backwards  enclosed  by  the  parotid 
o-land,  and  afterwards  between  the  meatus  auditorius  exter- 
mis  and  the  mastoid  bone;  at  the  latter  place,  it  sends  a ra- 
mification to  the.  internal  side  of  the  external  ear;  it  then 
ascends  and  is  distributed,  by  small  branches,  on  the  conti- 
guous integuments  of  the  side  of  the  head.  While  still  in- 
volved  in  the  parotid  gland,  it  sends  some  small  ramifications 
through  the  meatus  externus  to  its  lining  membrane  and  the 
membranatympani.  It  then  detaches  a branch  through  the 
stylo-mastoid  foramen,  from  which  the  whole  artery  is  also 
named  Stylo-Mastoid;  but  this  branch,  as  stated,  sometimes 
comes  from  the  occipital.  The  stylo-mastoid  passes  along 
the  aqueduct  of  Fallopius,  detaching  its  arterioles  to  the 
tympanum  and  to  the  labyrinth. 

The  External  Carotid  having  detached  these  trunks,  pe- 
netrates vertically  through  the  middle  of  the  parotid  gland, 
and  gives  to  it  several  small  twigs.  When  it  arrives  on  a 
line  with  the  neck  of  the  lower  jaw,  it  divides  into  two 
large  trunks;  one  of  them,  the  Internal  Maxillary,  goes  to 
the  parts  within  the  ramus  of  the  lower  jaw;  the  other,  be- 
ing smaller,  is  the  Temporal  Artery. 

The  Temporal  Artery  [Arteria  Te7n]joralis)  continues 
to  ascend  through  the  substance  of  the  Parotid,  but  becomes 
superficial  in  front  of  the  meatus  externus,  in  mounting  over 
the  root  of  the  zygoma;  it  is  then  distributed  to  the  integu- 
ments on  the  side  of  the  head. 

It  frequently  sends  off  one  or  two  ramifications,  of  but 
little  volume,  to  the  masseter  muscle.  Just  above  its  root, 
and  while  surrounded  by  the  parotid,  a branch  of  some  im- 
portance, the  Transversalis  Faciei,  leaves  it,  and  crosses 
horizontally  the  masseter  muscle,  just  below  the  Parotid 
Duct,  sometimes  above  it.  This  branch  is  distributed  to  the 
adjacent  integuments  and  muscles,  and  terminates  in  front 
by  anastomosing  with  the  facial  and  the  infra-orbitar  artery. 

A little  below  the  zygoma,  the  Middle  Temporal  Artery 


200 


CIRCULATORY  SYSTEM. 


comes  off  from  the  Temporal,  and,  ascending  with  the  pa- 
rent trunk,  perforates  the  temporal  fascia  at  the  upper  mar- 
gin of  the  zygoma,  and  is  distributed  to  the  temporal  mus- 
cle by  many  ramifications,  which  anastomose  with  the  deep- 
seated  temporal  arteries.  After  this,  some  small  twigs, 
called  Auricular,  go  to  the  external  ear  from  the  trunk  of 
the  Temporal  Artery. 

The  Temporal  Artery  having  ascended  for  an  inch  or  so 
between  the  aponeurosis  of  the  temporal  muscle  and  the 
skin,  divides  it  into  an  Anterior  and  a Posterior  Branch. 
The  former  ascends  towards  the  side  of  the  os  frontis, 
and  is  distributed  in  ramuscles  to  the  orbicularis  palpebra- 
rum, the  belly  of  the  occipito  frontalis,  and  the  integuments 
of  the  front  of  the  cranium,  anastomosing  with  the  frontal 
artery  and  the  temporal  of  the  other  side.  The  Posterior 
Branch  is  distributed  on  the  integuments  of  the  middle  of 
the  side  of  the  cranium,  anastomosing  with  the  anterior 
branch,  with  its  felloiV  of  the  other  side,  and  with  the  oc- 
cipital artery. 

The  Internal  Maxillary  Artery  {Jirteria  Maxillaris  In- 
terna) winds  around  the  neck  of  the  lower  jaw,  and  passing 
between  the  pterygoid  muscles,  proceeds  in  a tortuous  man- 
ner to  the  deepest  points  of  the  zygomatic  fossa.  The  first 
part  of  its  course  is  horizontally  inwards;  it  then  ascends  in 
front  of  the  pterygoideus  externus  to  the  bottom  of  the  tem- 
poral bone,  or  the  spinous  process  of  the  sphenoidal;  it  then 
passes  forwards,  within  the  temporal  muscle,  to  the  upper 
part  of  the  pterygo  maxillary  fossa. 

It  sends  off  several  branches,  and  commonly  in  the  fol- 
lowing order: 

1.  The  Arteria  Tympanica,  to  the  tympanum,  through 
the  glenoid  fissure. 

2.  The  Arteria  Meningea  Parva,  to  the  dura  mater, 
through  the  foramen  ovale.  It  is  most  frequently  a branch 
of  the  next. 

3.  The  Arteria  Meningea  Magna,  or  Media,  to  the  dura 
mater;  through  the  foramen  spinale.  This  branch  having 
entered  the  cranium,  is  distributed  upon  the  dura  mater  in 


CAK0TID3  AND  THEIR  BRANCHES.  201 

the  manner  marked  off  by  the  furrows  upon  the  internal 
face  of  the  temporal,  the  parietal,  and  the  frontal  bones. 
One  of  its  branches  enters  the  aqueduct  of  Fallopius,  through 
the  Vidian  Foramen,  and  is  distributed  upon  the  internal 
parts  of  the  organ  of  hearing,  anastomosing  with  the  stylo- 
mastoid artery. 

4.  The  Arteria  Maxillaris,  or  Dentalis  Inferior,  descends 
along  the  internal  face  of  the  ramus  of  the  lower  jaw,  and 
having  sent  off  some  ramifications  of  small  size  to  the  conti- 
guous muscles  and  the  lining  membrane  of  the  mouth,  it 
enters  the  posterior  mental  foramen  with  the  inferior  dental 
nerve.  Going  along  the  canal  in  the  substance  of  the  lower 
jaw,  it  detaches  successively  from  its  superior  margin  ra- 
mifications to  the  teeth.  At  the  anterior  mental  foramen  a 
trunk  is  sent  forward  as  far  as  the  symphysis,  which  sup- 
plies in  its  course  the  canine  and  incisor  teeth;  the  re- 
mainder of  the  inferior  maxillary  artery  comes  out  at  the 
foramen,  and  supplies  the  chin,  anastomosing,  with  the  facial 
artery. 

5.  The  Arteriaa  Temporales  Profundse  are  two  in  number. 
The  first  of  them,  called  posterior,  arises  next  to  the  infe- 
rior maxillary.  It  is  concealed  between  the  external  ptery- 
goid and  the  temporal  muscle  for  some  distance;  it  then 
ascends  in  the  posterior  part  of  the  temporal  fossa,  beneath 
the  temporal  muscle,  and  is  minutely  distributed  upon  it. 
The  anterior  deep  temporal  artery  is  separated  from  the 
posterior,  in  its  origin  from  the  internal  maxillary,  by  the 
pterygoid  and  the  buccal  arteries.  It  arises  near  the  ptery- 
go-maxillary  fossa,  and  ascending  between  the  temporal 
muscle  and  the  fore  part  of  the  corresponding  fossa,  it  is  mi- 
nutely distributed  upon  the  former,  anastomosing  with  the 
posterior  deep,  and  with  the  middle  temporal  artery. 

6.  The  Arterias  Pterygoidese  arise  after  the  posterior 
deep  temporal.  They  vary  considerably  in  regard  to  num- 
ber, size,  and  origin,  and  are  distributed  upon  the  ptery- 
goid muscles,  as  their  name  implies.  One  of  their  branches, 
which  is  sometimes  an  independent  trunk  from  the  internal 
maxillary,  goes  between  the  posterior  margin  of  the  tem- 

VoL.  II.— 26 


CIRCULATORY  SYSTEM. 


OAO 
^yJ/^ 

poral  muscle  and  of  the  neck  of  the  lower  jaw,  in  front  of 
the  latter,  to  be  distributed  upon  the  internal  face  of  the 
masseter  muscle. 

7.  The  Arteria  Buccalis,  sometimes  a branch  of  the  in- 
ternal maxillary,  but  frequently  coming  from  one  of  its 
trunks,  either  the  alveolar  or  the  anterior  temporal,  passes 
along  the  external  face  of  the  upper  jaw,  and  distributes  its 
branches  to  the  buccinator  and  zygomatic  muscles,  and  to 
the  lining  membrane  of  the  mouth. 

S.  The  Arteria  Maxillaris,  Superior,  or  Alveolaris,  pro- 
ceeds downwards  and  forwards  in  winding  around  the  tuber 
of  the  upper  jaw  bone.  It  first  sends  some  ramifications 
through  the  bone  to  the  roots  of  the  great  and  small  molar 
teeth,  and  to  the  lining  membrane  of  the  maxillary  sinus;  it 
then  passes  forwards  along  the  gums,  near  the  buccinator, 
and  gives  ramifications  to  them  and  to  the  contiguous  mus- 
cles. 

9.  The  Arteria  Infra-orbitalis  comes  from  the  internal 
maxillary,  at  the  upper  part  of  the  pterygo-maxillary  fossa; 
it  sends  some  inconsiderable  ramifications  to  the  fat  and  the 
periosteum  of  the  orbit,  through  the  spheno-maxillary  fis- 
sure. It  then  enters  the  infra-orbitary  canal,  and  passes 
through  it  with  the  infra-orbitary  nerve.  On  arriving  near 
the  anterior  orifice  of  the  canal,  it  detaches  downwards  a 
bi’anch  which  goes  to.  the  canine  and  the  incisor  teeth,  and 
to  the  lining  membrane  of  the  antrum.  It  then  gets  to  the 
face  below  the  origin  of  the  levator  labii  superioris  muscle, 
and  is  distributed  upon  the  muscles  in  front  of  the  upper 
maxilla,  anastomosing  with  the  facial  and  with  the  ophthal- 
mic artery. 

10.  The  Arteria  Palatina  Superior  descends  through  the 
posterior  palatine  canal,  and  having  reached  the  mouth, 
leaves  some  ramifications  with  the  soft  palate;  it  then  ad- 
-ances  between  the  bones  and  the  lining  membrane  of  the 
roof  of  the  mouth,  and  disperses  itself  in  several  small  twigs, 
one  of  which  passes  through  the  foramen  incisivum  into  the 
nostril. 

11.  The  Arteria  Pharyngea  Superior  is  sometimes  a 


SUBCLAVIAN  AND  ITS  BRANCHES. 


203 


branch  of  the  last,  and  is  spent  upon  that  portion  of  the 
pharynx  bordering  on  the  pterygoid  processes. 

12.  The  Arteria  Spheno-Palatina  is  the  terminating  trunk 
of  the  internal  maxillary;  it  enters  the  nose  through  the 
spheno-palatine  foramen,  and  divides  into  two  branches, 
which  are  minutely  distributed  over  the  Schneiderian  mem- 
brane. One  of  them  descends  along  the  septum  narium; 
the  other  along  the  external  margin  of  the  posterior  naris, 
and  divides  into  two  principal  ramuscles,  one  of  which  is 
dispersed  along  the  middle  turbinated,  and  the  other  along 
the  inferior  tubinated  bone. 


SECT.  III. OP  THE  SUBCLAVIAN  ARTERY  AND  ITS 

BRANCHES. 

The  Subclavian  Artery  {Arteria  Subcldvia)  of  the 
right  side  having  arisen  from  the  innominata,  and  that  of 
the  left  from  the  aorta,  they  each  go  over  the  first  rib  of  their 
respective  side,  adhering  closely  to  it,  in  the  bottom  of  the 
interval  between  the  scalenus  anticus  and  medius  muscles. 
The  right  subclavian  is  much  shorter,  and  more  superficial 
than  the  left,  from  its  origin  to  the  scaleni  muscles.  Near 
the  latter  they  are  each  covered  in  front  by  the  sternal  end 
of  the  clavicle,  by  the  sterno-hyoid.  and  thyroid  muscles, 
and  by  the  subclavian  vein  of  the  corresponding  side;  be- 
hind they  are  separated  from  the  vertebral  column  by  the 
longus  colli  muscle;  below  them  is  the  pleura,  the  left  ar- 
tery being  in  contact  with  it  for  its  whole  passage  in  the 
thorax;  and  on  their  internal  side  is  the  primitive  carotid. 
The  subclavian  of  the  right  side  is  crossed  near  the  scale- 
nus anticus  by  the  par  vagum ; the  phrenic  nerve  also  goes 
in  front  of  it,  but  on  the  internal  edge  of  the  scalenus. 
The  subclavian  of  the  left  side  having  a course  almost  ver- 
tical from  its  origin  to  the  interval  of  the  scaleni  muscles, 
is  nearly  parallel  with,  and  behind,  the  primitive  carotid  of 
that  side;  the  phrenic  nerve  has  the  same  relative  position 
with  it  as  on  the  right  side;  but  the  par  vagum  goes  paral- 


2U1 


CIRCULATORY  SYSTEM. 


lei  with,  and  in  front  of  the  subclavian  artery,  for  some 
distance  along  the  root  of  the  latter. 

At  the  inner  margin  of  the  Scaleni  Muscles  the  Subcla- 
vian gives  off  a cluster  of  trunks,  to  wit;  the  Vertebral; 
the  Inferior  Thyroidal;  the  Superior  Intercostal;  the  In- 
ternal Mammary;  and  the  Cervical  Artery.  They  some- 
times arise  distinctly,  and  after  the  order  mentioned;  but 
there  is  too  great  a diversity  in  subjects  to  establish  any 
rule  on  these  points. 

1.  The  Vertebral  Artery  {A'teria  Veriehralis)  is  the 
most  voluminous  of  the  branches  of  the  Subclavian.  Im- 
mediately after  its  origin  it  ascends  on  the  side  of  the  spine 
and  enters  the  canal  of  the  transverse  processes  of  the  neck 
at  the  sixth  vertebra.  Pursuing  this  course  it  gets  into  the 
cavity  of  the  cranium  through  the  foramen  magnum  occipi- 
tis,  and  is  distributed  to  the  brain  in  the  manner  mention- 
ed in  the  description  of  that  organ. 

While  in  the  canal  of  the  transverse  processes  it  sends 
off  several  branches  to  the  heads  of  the  contiguous  mus- 
cles, and  to  the  medulla  spinalis  of  the  neck. 

2.  The  Inferior  Thyroid  Artery  {^rteria  Thyroidea 
Inferior)  arises  from  the  upper  face  of  the  subclavian,  and 
goes  to  the  thyroid  gland.  It  ascends  at  first  on  the  inter- 
nal margin  of  the  scalenus  medius  muscle,  and  then  turns 
suddenly  inwards  between  the  vertebrae  and  the  great  ves- 
sels of  the  neck. 

In  this  course  several  unimportant  twigs  are  sent  from 
it  to  the  contiguous  parts.  Near  its  root  it  detaches  the 
Anterior  or  the  Ascending  Cervical  Artery,  which  going  up 
the  neck  is  spent  upon  the  heads  of  the  muscles  arising 
from  the  transverse  processes,  as  the  scaleni,  the  longus 
colli,  and  so  on.  The  inferior  thyroidal  then  gets  to  the 
thyroid  gland,  and  is  very  minutel)'^  distributed  to  it,  anas- 
tomosing with  the  other  arteries  which  supply  the  same 
organ. 

3.  The  Superior  Intercostal  Artery  {Jirteria  Tniercosta 


SUBCLAVIAN  AND  ITS  BRANCHES. 


205 


lis  Supei'ior)  arising  from  tlie  under  surface  of  the  subcla- 
vian opposite  the  inferior  thyroid,  descends  across  the  neck 
of  the  first  rib,  and  divides  into  two  branches,  which  sup- 
ply the  two  upper  intercostal  spaces:  each  of  them  also 
sends  backwards  near  the  vertebrae  a small  trunk  to  the 
muscles  of  the  back. 

4.  The  Internal  Mammary  Artery  {Jlrteria  Mammaria 
Interna.  Thoracica)  descends  at  first  along  the  internal 
margin  of  the  scalenus  anticus;  having  then  got  fairly  into 
the  cavity  of  the  thorax,  it  continues  to  descend  across  the 
posterior  face  of  the  costal  cartilages,  parallel  with,  and 
about  nine  lines  from,  the  outer  edge  of  the  sternum,  be- 
tween the  triangularis  sterni  and  the  intercostal  muscles. 

In  this  course,  besides  some  distinct  twigs  to  the  anterior 
mediastinum,  it  sends  a branch  which  accompanying  the 
phrenic  nerve  between  the  pleura  and  the  pericardium, 
reaches  finally  the  diaphragm,  and  is  spent  upon  it.  At 
each  intercostal  space  which  it  crosses,  the  internal  mam- 
mary sends  off  one' branch,  which  is  spent  upon  the  fore 
part  of  the  intercostal  muscles,  and  anastomoses  with  the 
corresponding  intercostal  artery;  other  branches  also  leave 
it  at  each  space,  which  getting  forwards  near  the  sternum, 
are  distributed  upon  the  pectoralis  major,  and  upon  the  con- 
tiguous muscles.  The  last  of  these  branches,  according  to 
M.  H.  Cloquet,  goes  transversely  over  the  ensiform  carti- 
tilage,  and  having  anastomosed  with  its  fellow  descends  be- 
tween the  peritoneum  and  the  linea  alba  to  the  suspensory 
ligament  of  the  liver. 

On  a line  generally  with  the  anterior  extremity  of  the 
fifth  rib,  the  internal  mammary  divides  into  two  principal 
branches;  the  most  exterior  of  which,  descending  along  the 
cartilaginous  margin  of  the  thorax,  is  distributed  in  small 
twigs  to  the  origin  there  of  the  diaphragm  and  of  the  trans- 
verse muscle  of  the  abdomen.  The  internal  branch  reaches 
the  posterior  face  of  the  rectus  abdominis  muscle  and  is 
dispersed  upon  it;  some  of  its  branches  reach  as  low  as  the 
umbilicus  to  anastomose  there  with  the  epigastric  artery. 


20G 


CIRCULATORY  SYSTEM. 


5.  The  Posterior  Cervical  Artery  [Arteria  Cervicalis 
Posterior,  Transversa)  is  of  a ver)'-  unsettled  origin,  but 
comes  most  frequently  either  from  the  subclavian  itself,  or 
from  the  inferior  thyi’oid.  It  is  but  small  in  some  subjects, 
owing  to  its  place  being  supplied  by  branches  from  the  ad- 
joining arteries. 

It  crosses  horizontally  the  root  of  the  neck  on  the  outer 
face  of  the  scaleni  muscles  above  the  subclavian  artery.  It 
gets  under  the  anterior  margin  of  the  trapezius,  and  is 
there  divided  into  two  principal  branches;  the  ascending- 
one  is  spent  upon  the  trapezius  and  the  levator  scapulae;  the 
other  descends  along  the  base  of  the  scapula,  and  is  spent 
in  ramifications  upon  the  rhomboideus  and  the  serratus 
magnus  muscles.  Several  branches  of  minor  size  and  im- 
portance are  sent  off  from  the  posterior  cervical  artery  to 
the  muscles  on  the  back  of  the  neck  and  thorax. 

The  Subclavian  artery  having  sent  olf  the  preceding 
branches,  then  escapes  from  the  thorax  between  the  scaleni 
muscles,  and  gets  to  the  arm-pit  between  the  first  rib  and 
the  subclavius  muscle.  The  trunk  of  it  is  then  continued 
downwards  through  the  axilla,  and  at  the  inner  side  of  the 
ai-m  to  the  elbow  joint. 

From  the  scaleni  muscles  to  the  elbow  its  relative  posi- 
tion is  as  follows:  When  it  first  appears  between  the  scale- 
ni, it  is  bounded  above  and  behind  by  the  collected  fasci- 
culi of  the  axillary  plexus  of  nerves.  In  front  it  is  sepa- 
rated from  the  subclavian  vein  by  the  insertion  of  the 
scalenus  anticus.  It  is  placed  at  the  bottom  of  the  depres- 
sion between  the  sterno  mastoideus  and  the  trapezius,  being 
covered  by  the  skin,  the  platysma  myoides,  and  some  loose 
cellular  substance  below  the  latter.  It  then  descends  be- 
tween the  first  rib  and  the  subclavius;  escaping  from  below 
the  latter,  it  is  covered  in  front  by  the  outer  margin  of  the 
pectoralis  major  until  it  reaches  the  lower  part  of  the  ax- 
illa: and  in  this  course  it  has  the  following  relation  to  other 
parts;  it  passes  under  the  shoulder  joint,  then  under  the  in- 
sertion of  the  pectoralis  minor,  then  along  the  internal  face 


SUBCLAVIAX  AND  ITS  BEANCHES.  207 

of  the  coraco  brachialis  muscle;  it  has  the  axillary  vein  in 
front  of  it  and  the  axillary  nerves  plaited  around  it  as  far 
down  as  the  coracoid  process,  when  they  begin  to  disperse. 
This  artery  in  emerging  from  the  axilla  is  placed  upon  the 
anterior  face  of  the  insertion  of  the  latissimus  dorsi;  it  then 
runs  out  the  length  of' the  coraco  brachialis,  and  is  . after- 
wards conducted  along  the  innef  margin  of  the  biceps  flexor 
cubiti  and  its  tendinous  termination;  it  lies  upon  the  ante- 
terior  face  of  the  brachialis  internus;  and  goes  beneath  the 
aponeurosis  at  the  bend  of  the  arm,  coming  from  the  ten- 
don of  the  biceps.  In  the  arm  it  is  concealed  only  by  the 
integuments  and  fascia,  and  is  bordered  internally  by  the 
brachial  vein  and  the  median  nerve. 

This  great  trunk  of  the  upper  extremity  loses  the  name 
of  subclavian  to  be  called  Axillary  Artery,  {Art.  Axilla- 
ris, ) from  the  subclavian  muscle  to  the  lower  margin  of  the 
arm-pit;  and  from  the  latter  place  to  the  elbow  joint,  it  is 
named  Brachial  Artery,  {Art.  Brachialis.)  It  sends  off 
many  interesting  branches  to  the  thorax,  to  the  shoulder, 
and  to  the  arm;  and  finally  terminates  a little  below  or  at 
the  elbow  joint  by  bifurcating. 

Of  the  Branches  of  the  Axillary  Artery. 

1.  The  Superior  Scapular  Artery  {Art.  Dorsalis  Supe- 
rior Scapulse)  varies  considerably  in  its  origin.  Some- 
times it  is  a branch  of  the  subclavian,  sometimes  of  the  in- 
ferior thyroid,  and  it  frequently  comes  from  the  upper  part 
of  the  axillary,  so  that  it  cannot  be  referred,  with  strict  pro- 
priety, to  any  determined  origin.  When  it  comes  from 
the  axillary,  it  is  very  tortuous  and  has  to  ascend  to  its  des- 
tination,, which  removes  it  entirely  from  any  interference 
with  the  course  of  the  subclavian  over  the  first  rib,  and 
over  the  upper  head  of  the  serratus  magnus  muscle.  But 
in  the  other  cases,  it  goes  transversely  backwards  and  out- 
wards, somewhat  below  the  posterior  cervical,  and  along 
the  posterior  inferior  margin  of  the  clavicle,  being  covered 
by  the  sterno-mastoideus,  the  platysma  myoides,  and  the 


20S 


CIRCULATORY  SYSTEM. 


trapezius;  consequently  it  is  just  in  the  way  of  the  incisions 
which  are  made  for  reaching  the  subclavian  artery,  from 
above  the  clavicle. 

It  reaches  the  superior  costa  of  the  scapula  near  the  root 
of  the  coracoid  process,  and  passing  through  the  notch 
there,  is  distributed,  by  one  large  branch,  upon  the  supra- 
spinatus  muscle;  and  by  another,  which  goes  across  the  an- 
terior margin  of  the  spine  of  the  scapula,  to  the  infra-spi- 
natus  muscle.  In  its  course,  it  sends  off  several  small  ra- 
mifications to  contiguous  parts. 

2.  The  External  Mammary  Arteries  Mammarise 

seu  Thoracicae  Externae)  arise  from  the  axillary,  between 
the  subclavius  and  the  pectoralis  minor  muscles.  They 
are  four  principal  trunks,  which  go  uniformly  to  certain 
parts,  but  vary  considerably  in  their  origin;  for  sometimes 
the  latter  is  distinct  in  the  case  of  each  artery,  but  frequent- 
ly otherwise.  Their  distribution  is  as  follows: 

a.  The  Thoracica  Superior  is  distributed  to  the  upper 
part  of  the  pectoralis  major  muscle,  and  to  the  pectoralis 
minor.  Some  of  its  branches  reach  the  mamma  in  the  fe- 
male, and  anastomose  with  the  internal  mammary  and  with 
the  intercostals. 

b.  The  Thoracica  Longa  descends  along  the  posterior 
face  of  the  pectoralis  major,  between  it  and  the  serratus 
magnus.  It  gives  many  branches  to  the  lower  part  of  the 
pectoralis  major,  to  the  integuments,  and  in  the  female  to 
the  mamma;  anastomosing  likewise  with  the  internal  mam- 
mary and  with  the  intercostals. 

c.  The  Thoracica  Acromialis,  immediately  after  its  ori- 
gin, makes  for  the  fissure  between  the  deltoid  and  the  great 
pectoral  muscle,  and  divides  there  into  an  ascending  and  a 
descending  branch.  The  former  reaches  the  clavicle,  and 
is  partly  distributed  superficially  along  it,  partly  to  the  con- 
tiguous muscles  and  to  the  shoulder  articulation.  The  other 
branch  follows  the  cephalic  vein  along  the  interstice  between 
the  deltoides  and  pectoralis  major,  and  is  finally  distributed 
to  these  muscles  and  to  the  integuments. 


AXILLARY  ARTERY. 


209 


d.  The  Thoracica  Axillaris  is  irregular,  both  in  I’egard  to 
the  number  of  its  branches  and  to  their  origin.  Instead  of 
a distinct  origin  b)''  one  or  more  trunks  from  the  axillary 
artery,  the  branches  belonging  to  tbe  name  of  thoracica  ax- 
illaris, are  sometimes  derived  from  the  other  thoracic  arte- 
ries. They  are  generally  distributed  only  to  the  fat  and 
the  lymphatic  glands  in  the  axilla.  They  occasionally  ex- 
ist primitively  as  a large  trunk,  which  runs  on  the  scapular 
face  of  the  serratus  magnus  the  whole  length  of  the  scapula, 
and  is  distributed  to  the  adjacent  muscles,  and  to  the  fat 
and  glands  of  the  axiHa. 

3.  The  Scapular  Artery  {Jirleria  Scapularis  commu- 
nis, Suhscapularis)  arises  from  the  axillary  below  the  shoul- 
der joint,  at  or  near  the  anterior  margin  of  the  subscapula- 
ris  muscle.  Giving  off  some  inconsiderable  branches  to  the 
lymphatic  glands  of  the  arm-pit,  it  descends  along  the  an- 
terior margin  of  the  suhscapularis,  and  is  distributed  to  it, 
to  the  latissimus  dorsi,  and  to  the  teres  major  and  minor 
muscles. 

A little  below  the  neck  of  the  scapula,  it  detaches  a large 
trunk,  the  Dorsalis  Inferior  Scapulae,  which,  winding  around 
the  inferior  costa  of  the  bone  over  the  anterior  margin  of 
the  suhscapularis  and  the  teres  minor,  reaches  the  fossa  in- 
fra-spinata.  This  trunk  then  divides  into  two  branches: 
one  of  which  is  distributed  superficially  between  the  apo- 
neurosis and  the  infra-spinatus,  and  the  other  more  deeply 
near  the  dorsum  of  the  bone:  one  of  the  ramuscles  of  the 
latter  ascends  beneath  the  neck  of  the  acromion  to  anasto- 
mose with  the  Dorsalis  Superior  Scapulae. 

4.  The  Anterior  Circumflex  Artery  {Art.  Circmnjlexa 
Anterior,  Articularis  Anterior)  is  about  the  size  of  a crow 
quill,  and  arises  from  the  axillary  just  above  the  tendon  of 
the  teres  major  and  of  the  latissimus  dorsi.  It  adheres 
closely  to,  and  surrounds  the  front  of  the  neck  of  the  os 
humeri,  passing  between  it,  the  coraco-brachialis,  and  the 
short  head  of  the  biceps.  It  then  divides  into  several 

VoL.  II.— 27 


C]  liCVI-ATOHV  SYSTjEM. 


J .1  U 

branches,  some  of  wliich  go  to  the  deltoides  and  anastomose 
there  with  the  posterior  circumflex;  others  go  immediate- 
ly to  the  articulation,  and  either  terminate  on  it  or  ascend 
to  the  muscles  on  the  dorsum  of  the  scapula,  where-  they 
anastomose  with  the  scapular  arteries. 

The  Posterior  Circumflex  Artery  Circumjlexa 

Poster'ior)  is  much  larger  than  the  last,  and  arises  from  the 
axillary  somewhat  below  it.  It  surrounds  the  posterior  face 
of  the  neck  of  the  os  humeri,  passing  between  it  and  the 
long  head  of  the  triceps  muscle,  below  the  insertion  of  the 
teres  minor.  Many  of  its  ramiflcations  go  to  the  capsular 
ligament  of  the  articulation  and  to  the  muscles  adhering  to 
it.  But  this  artery  is  principally  intended  for  the  deltoid 
muscle,  to  the  internal  face  of  which  the  most  of  its  branches 
go.  It  anastomoses  with  the  anterior  circumflex,  and  with 
the  scapular  arteries. 

In  some  cases,  the  posterior  circumflex  arises  from  the 
axillary  below,  instead  of  above  the  tendinous  insertion  of 
the  latissimus  dorsi;  when  this  happens,  it  commonly  gives 
oflT  the  arteria  jirofunda  major  of  the  arm,  and  afterwards 
ascends  on  the  posterior  face  of  the  tendon  to  its  appropriate 
destination. 

Of  the  Branches  of  the  Brachial  Srtery. 

1.  The  Profound  Artery  {Arteria  Prof  unda  Major  Hu- 
meri, Spiralis)  arises  from  the  brachial,  a little  below  the 
tendinous  insertion  of  the  latissimus  dorsi;  and  having 
passsed  downwards,  for  a short  distance,  it  enters  the  inter- 
stice between  the  first  and  the  third  head  of  the  triceps  mus- 
cle, and  winds  spirally  downwards  around  the  os  humeri  in 
company  with  the  radial  nerve.  On  the  outer  side  of  the 
arm,  it  becomes  superficial  between  the  margins  of  the  tri- 
ceps and  of  the  brachialis  internus,  and  then  directs  its 
course  between  the  latter  and  the  supinator  longus  to  the 
external  condyle. 

In  this  course,  the  artery  sends  several  branches  to  the 
triceps  muscle,  to  which,  indeed,  it  is  principally  destined. 


AXILLARY  ARTERY. 


211 


Near  the  external  condyle,  it  supplies  the  brachialis  inter- 
nus  and  the  heads  of  the  extensor  muscles  of  the  fore-arm, 
and  anastomoses  with  the  recurrent  branch  of  the  radial  ar- 
tery. 

2.  The  Small  Profound  Artery  Profunda  Minor) 
comes  from  the  brachial,  two  or  three  inches  below  the 
profunda  major,  but  frequently  it  is  only  a branch  of  the 
latter,  and  is  generally  much  smaller.  It  is  distributed  su- 
perficially on  the  internal  face  of  the  triceps  at  its  lower 
part,  and  has  its  terminating  branches  reaching  as  far  as  the 
internal  condyle. 

3.  The  Nutritious  Artery  {<Mrt.  Nutritia)  is  the  next  in 
order  from  the  brachial;  and  arises  from  it  near  the  medul- 
lary foramen  of  the  os  humeri,  through  which  it  penetrates 
and  is  distributed  to  the  lining  membrane  of  the  bone.  It 
is  not  larger  than  a knitting  needle. 

4.  The  Anastomotic  Artery  {Arteria  Anastomotica) 
arises  from  the  brachial  below  the  last,  and  is,  larger  than  it. 
It  lies  upon  the  lower  internal  part  of  the  brachialis  internus 
muscle,  and  crosses  the  ridge  leading  to  the  internal  condyle 
in  order  to  reach  the  depression  between  the  latter  and  the 
olecranon,  where  it  anastomoses  with  the  ulnar  recurrent  ar- 
tery. 

The  preceding  is  a common  arrangement  of  the  branches 
proceeding  from  the  brachial  artery,  }^et  deviations  from  it 
are  continually  met  with,  in  a deficiency  or  in  a redundancy 
of  these  collateral  trunks,  and  in  their  mode  of  origin.  An 
account  of  all  the  varieties  which  are  observed  here  would 
be  almost  endless,  as  every  subject  has  some  peculiarity. 
Several  small  arteries  are  also  sent  from  the  brachial  to  the 
coraco-brachialis,  the  biceps,  the  brachialis  internus,  and  to 
the  triceps  muscles.  They  for  the  most  part  are  simply 
muscular  branches,  which  are  too  small  and  irregular  to  de- 
serve specifying. 

The  division  of  the  brachial  artery  into  the  two  trunks, 


'212 


GIRCULATOKV  SYSTEM. 


the  Radial  and  the  Ulnar,  will  be  found  in  a majority  of  sub- 
jects in  front  of  the  brachialis  internus  muscle  on  a line  with 
the  elbow  joint,  sometimes  it  occurs  nearer  the  root  of  the 
coronoid  process.  It  is  however  by  no  means  rare  to  see 
this  bifurcation  much  above  the  elbow.  Examples  of  it  have 
been  witnessed  at  every  point  between  the  latter  and  the 
arm-pit;  in  such  cases  the  course  of  the  radial  artery  down 
the  fore-arm  is  generally  much  more  superficial  than  usual, 
as  it  is  placed  immediately  below  the  skin. 

Of  tht  Radial  Jirtery. 

The  Radial  Artery  {Arteria  Radialis)  is  smaller  than  the 
ulnar,  and  extends  from  the  elbow  to  the  hand.  In  the 
upper  half  of  the  fore-arm  it  is  placed  at  the  bottom  of  the 
fissure  between  the  supinator  radii  longus  and  the  pronator 
teres  muscle.  Having  crossed  the  insertion  of  the  latter,  it 
runs  in  front  of  the  radius,  between  the  tendon  of  the  supi- 
nator and  of  the  flexor  carpi  radialis.  Below  the  styloid 
process  of  the  radius  it  runs  between  the  outer  end  of  the 
carpus  and  the  extensor  muscles  of  the  thumb;  it  then  pene- 
trates to  the  palm  of  the  hand  between  the  root  of  the  meta- 
carpal bone  of  the  thumb  and  of  the  fore-finger,  above  the 
abductor  indicis  muscle. 

The  following  branches  are  sent  from  the  Radial  Ar- 
tery. 

1.  The  Recurrens  Radialis  arises  at  the  neck  of  the  ra- 
dius. It  winds  externally  around  the  joint  between  the  ex- 
ternal condyle  and  the  muscles  coming  from  it,  and  an- 
astomoses with  the  spiralis  of  the  humeral  artery,  being 
distributed  in  many  collateral  branches,  to  the  joint  and  to 
the  contiguous  muscles. 

2.  Several  small  and  irregular  muscular  branches  arise 
from  the  radial  artery,  in  its  progress  to  the  wrist;  they  have 
no  appropriated  names. 


ULNAR  ARTERY. 


213 


3.  The  Superficialis  Volse  arises  from  the  radial  about  the 
inferior  margin  of  the  pronator  quadratus  muscle.  It  passes 
superficially  over  the  process  of  the  trapezium  to  the  mus- 
cles of  the  ball  of  the  thumb,  and  one  of  its  terminating 
branches  joins  the  arcus  sublimis.  Sometimes  the  superfi- 
cialis volae  is  the  principal  branch  of  the  radial. 

4.  The  Dorsalis  Carpi  arises  from  the  radial  at  the  car- 
pus, runs  across  the  back  of  the  latter  below  the  extensor 
tendons,  and  detaches  the  posterior  interrosseous  arteries  of 
the  back  of  the  hand.  They  anastomose  with  branches  from 
the  ulnar  and  interosseous  arteries  of  the  fore-arm. 

5.  The  Magna  Pollicis,  a terminating  branch  of  the  ra- 
dial, comes  from  it  in  the  palm  of  the  hand  just  at  the  root 
of  the  metacarpal  bone  of  the  thumb.  It  runs  beneath  the 
abductor  indicis,  and  at  the  head  of  the  metacarpal  bone  di- 
vides into  two  branches  which  run  along  the  sides  of  the 
thumb  to  its  extremity,  where  they  anastomose  and  termi- 
nate. 

6.  The  Radialis  Indicis,  arising  at  the  same  place  with 
the  latter,  runs  along  the  metacarpal  bone  of  the  fore-finger, 
and  along  the  radial  side  of  the  same  finger  to  its  extremity. 

7.  The  Palmaris  Profunda  is  the  third  terminating  branch 
of  the  radial  artery.  It  arises  near  the  same  place  with  the 
two  last,  crosses  the  hand  betvveen  the  metacarpal  bones 
and  the  flexor  tendons;  thus  forming  the  Arcus  Profundus, 
from  which  branches  proceed  to  the  interossei  muscles,  and 
which  ends  on  the  ulnar  side  of  the  palm  of  the  hand  by  a 
branch  to  the  Arcus  Superficialis. 

Of  the  Ulnar  Jittery. 

The  Ulnar  Artery  {Arteria  Ulnaris)  one  of  the  forks  of 
the  brachial  at  the  elbow,  passes  more  in  a line  with  it  than 
the  radial  artery  does.  It  goes,  immediately  after  its  origin, 


214 


CIRCULATORY  SYSTEM. 


under  several  of  the  muscles  of  the  internal  condyle,  to 
wit:  the  pronator  teres,  flexor  radialis,  flexor  sublimis,  and 
palmaris  longus,  and  between  the  flexor  sublimis  and  pro- 
fundus digitorum,  being  deeply  seated;  getting  from  beneath 
the  flexor  sublimis,  it  afterwards  runs  parallel  with  tlie  ulna 
or  nearly  so,  lying  on  the  flexor  profundus  between  the 
flexor  ulnaris  and  the  ulnar  margin  of  the  flexor  sublimis, 
and  concealed  two-thirds  of  the  way  down  the  fore-arm  by 
the  overlapping  of  these  muscles.  At  the  thin  part  of  the 
fore-arm,  commonly  called  the  wrist,  it  is  superficial,  and 
may  be  felt  pulsating  in  the  living  body  at  the  radial  margin 
of  the  tendon  of  the  flexor  ulnaris. 

The  ulnar  artery,  at  the  carpus,  takes  a very  different 
course  from  ihe  radial,  for  it  passes  over  the  anterior  annu- 
lar ligament  of  the  carpus  just  at  the  radial  side  of  the  os 
pisiforme,  to  which  it  is  held  by  a small  ligamentous  noose; 
it  then  proceeds  to  the  palm  of  the  hand.  Between  the  apo- 
neurosis palmaris  and  the  flexor  tendons  it  forms  that  curve 
from  the  ulnar  to  the  radial  side  of  the  hand  called  the  Arcus 
Sublimis.  This  curve  commonly  begins  a little  beyond  the 
anterior  margin  of  the  annular  ligament,  and  presenting  its 
convexity  forwards,  terminates  about  the  middle  of  the  ball 
of  the  thumb  at  its  inner  margin. 

The  branches  sent  from  the  ulnar  artery  are  as  follow: 

1.  The  Recurrens  Ulnaris  arises  from  the  ulnar  about  the 
lower  part  of  the  tubercle  of  the  radius,  and  winding  up- 
wards is  distributed  in  small  branches  to  the  muscles  of  the 
internal  condyle.  One  of  its  ramuscles  goes  between  the 
internal  condyle  and  the  olecranon  process  to  anastomose 
with  the  arteria  anastomotica  of  the  humeral. 

2.  The  Interossea  arises  from  the  ulnar  just  below  the 
other.  It  is  a large  trunk,  and  proceeds  but  a little  distance 
when  it  divides  into  two  principal  branches,  called  anterior 
and  posterior  interosseal  arteries. 

a.  The  Interossea  Anterior  is  much  the  larger;  it  runs  in 
contact  with  the  interosseous  ligament  to  the  upper  margin 


ULNAR  ARTERY. 


215 


V 


of  the  pronator  quadratus,  giving  off  branches  to  the  deep- 
seated  muscles  of  the  fore-arm  in  its  course.  Under  the  pro- 
nator it  perforates  the  interosseous  ligament  and  disti’ibutes 
branches  to  the  back  of  the  carpus  and  of  the  hand,  which 
anastomose  with  branches  of  the  radial  and  posterior  inter- 
osseal. 

h.  The  Interossea  Posterior  is  sometimes  a separate  trunk, 
arising  from  the  ulnar  just  above  the  former.  In  either  case 
it  soon  perforates  the  interosseous  ligament  to  get  to  the 
back  of  the  fore-arm.  Here  it  sends  backwards  a Recurrent 
Branch  to  the  back  of  the  elbow,  which  anastomoses  with 
the  recurrens  ulnaris  and  radialis.  It  then  proceeds  down- 
wards, being  deeply  seated  and  distributed  to  the  different 
muscles  on  the  back  of  the  fore-arm.  Some  of  its  branches 
reach  the  wrist,  and  anastomose  with  the  carpal  arteries. 

3.  The  ulnar  artery,  in  its  descent  on  the  fore-arm,  sends 
off  many  small  and  irregular  muscular  branches  called  by 
Professor  Chaussier,  Cubito-musculaires:  they  do  not  re- 
quire description. 

4.  The  Dorsalis  Manus  leaves  the  ulnar  at  the  lower  end 
of  the  fore-arm,  and  passes  under  the  tendon  of  the  flexor 
ulnaris  to  the  back  of  the  hand.  It  there  meets  raniuscles 
of  the  radial  and  interosseous,  and,  conjointly  they  supply 
with  very  small  branches  the  back  of  the  wrist,  of  the  me- 
tacarpus and  of  the  fingers. 

5.  As  the  Arcus  Sublimis  is  about  beginning,  the  ulnar 
artery  sends  superficial  but  small  branches  to  the  integu- 
ments of  the  palm:  and  a little  further  on,  a considerable 
branch,  which  dives  into  the  bottom  of  the  palm,  through 
the  muscles  of  the  little  finger,  and  joins  the  ulnar  extre- 
mity of  the  arcus  profundus;  this  is  the  Cubitalis  Manus 
Profunda  of  Haller. 

6.  The  Arcus  Sublimis  then  sends  a branch  to  the  ulnar 
side  of  the  little  finger.  Afterwards  in  succession  three  di- 
gital branches  are  sent  off,  which,  arriving  at  the  interstices 


S16 


C1KCUI.AT0RY  SYSTEM. 


between  the  heads  of  the  metacarpal  bones,  each  divides 
into  two  branches  to  supply  the  sides  of  the  fingers  which 
are  opposite  to  each  other;  one  branch  is  called  Digito-radial, 
the  other  Digito-ulnar,  according  to  the  side  of  the  finger  on 
which  the  artery  may  be  placed. 

The  Digital  Arteries,  before  they  divide,  receive  each  a 
small  branch  from  the  arcus  profundus.  The  digito-radial, 
and  the  digito-ulnar  arteries,  pass  along  the  sides  of  the 
fingers  in  front  to  their  extremities;  at  the  joints  and  extre- 
mities, anastomoses  between  the  arteries  of  the  two  sides  of 
the  same  finger  frequently  occur. 

The  arcus  sublimis  terminates  on  the  radial  side  of  the 
palm  by  a branch  which  joins  the  inner  branch  of  the  Ar- 
teria  Magna  Pollicis  of  the  Radial. 

The  most  frequent  arrangement  of  the  arteries  of  the  hand 
is  what  has  been  just  described;  anatomists  are,  however, 
not  all  agreed  on  this  point.  It  would  probably  be  more  just 
to  say,  judging  from  our  collection  in  the  University,  that 
this  occurs  more  than  any  other  single  arrangement.  The 
varieties,  in  fact,  are  so  gi’eat,  that  before  a hand  is  opened, 
it  is  not  possible  to  know  in  what  manner  its  arteries  will 
be  distributed.  Sometimes  the  Radial  Artery  furnishes  one 
half  of  the  arcus  sublimis,  and  the  Ulnar  the  other  half.  On 
other  occasions,  the  interosseous  artery  is  continued  as  a 
large  trunk  over  the  ligament  of  the  wrist,  and  across  the 
root  of  the  thumb,  to  join  the  arcus  sublimis. 

SECT.  IV. — BRANCHES  OP  THE  DESCENDING-  THORACIC 
AORTA. 

The  Aorta,  in  its  course  from  the  lower  part  of  its  curva- 
ture to  the  crura  of  the  Diaphragm,  gives  off  several  branches 
to  the  viscera  and  to  the  parietes  of  the  thorax. 

The  Bronchial  Arteries,  {Jirterise  Bronchiales)  are  the 
nutritious  vessels  of  the  lungs.  There  is  commonly  one  for 
each  lung,  but  sometimes  two  or  more.  The  right  arises 
frequently  from  the  superior  intercostal  artery,  instead  of 


BRANCHES  OP  THE  THORACIC  AORTA. 


217 


from  the  aorta,  while  the  left  conies  from-  the  latter;  occa- 
sionally they  have  a common  root. 

On  either  side  they  follow  the  course  of  the  bronchia  into 
the  substance  of  the  lung;  and  are  distributed  along  with  it, 
by  ramifications  which  become  successively  finer  and  finer, 
and  anastomose  with  the  pulmonary  artery;  after  the  man- 
ner mentioned  in  the  description  of  the  lungs.  Before  they 
enter  the  latter  they  send  some  small  ramifications  to  the 
posterior  mediastinum,  to  the  pericardium,  and  to  the  black 
bronchial  glands. 

The  CEsophageal  Arteries  {Jirterise.  CEsophagese)  are 
generally  five  or  six  small  twigs  which  come  successively 
from  the  descending  thoracic  aorta.  They  ramify  minutely 
in  the  substance  of  the  oesophagus,  communicating  freely 
with  each  other;  the  lowest  of  them  also  anastomoses  around 
the  cardia  with  the  superior  coronary  artery  of  the  stomach. 

The  posterior  Arteries  of  the  Mediastinum,  {Arterise  Me- 
diastinales  Posteriores,)  are  numerous  and  small;  they 
come  from  the  anterior  face  of  the  aorta,  as  well  as  from  the 
branches  last  mentioned;  and  are  spent  upon  the  posterior 
mediastinum,  and  upon  its  contents. 

The  intercostal  Arteries  {Jlrteriss  Intercostales  inferiores 
aorticse)  of  the  aorta  supply  the  ten  lower  intercostal  spaces 
on  each  side,  as  the  two  upper  ones  are  supplied  by  the  sub- 
clavian artery.  There  is  commonly  an  intercostal  artery 
arising  distinctly  from  the  aorta  for  each  space,  but  some- 
times two  of  them  arise  from  a common  trunk.  Those  for 
the  right  side  having  to  cross  the  spine  behind  the  oesopha- 
gus and  the  vena  azygos,  are,  of  course,  longer  than  such  as 
belong  to  the  left.  The  upper  ones  on  either  side  have  to 
ascend,  in  order  to  reach  their  destination. 

Each  artery  joins  the  rib  near  its  tubercle,  and  goes  along 
the  groove  in  its  lower  margin,  between  the  external  and  the 
internal  intercostal  muscles,  for  two-thirds  of  the  length  of 
the  rib.  It  then  abandons  the  groove,  and  divides  into  seve- 
Voi.  II. — 28 


CIRCULATORY  SYSTEM. 


iilS 

ral  branches,  which  go  to  the  intercostal  muscles  and  conti- 
guous parts,  anastomosing  in  front  with  the  internal  mam- 
mary artery. 

As  each  intercostal  artery  passes  the  head  of  the  rib,  it 
sends  a branch  backwards,  {ramus  dorsalis,)  between  the 
transverse  processes  of  the  adjoining  vertebrae,  which  pe- 
netrates to  the  posterior  face  of  the  trunk,  and  is  distri- 
buted to  the  muscles  and  skin  on  the  side  of  the  spine.  A 
ramification  from  this  branch  enters  the  intervertebral  fora- 
men, and  is  spent  upon  the  medulla  spinalis  and  its  mem- 
branes. 

Each  intercostal  artery  also  gives  off,  about  the  middle  of 
the  rib,  a branch,  {ramus  costalis  inferior,)  much  smaller 
than  the  trunk.  This  branch  advances  along  the  upper  mar- 
gin of  the  rib  below,  and  gives  ramifications  to  its  periosteum 
and  to  the  adjacent  intercostal  muscles. 

The  last  intercostal  artery  is  remarkable  for  its  size.  Its 
origin  is  concealed  by  the  small  muscle  of  the  diaphragm,  to 
which  it  gives  some  ramifications;  it  then  passes,  at  the 
under  margin  of  the  rib,  behind  the  upper  end  of  the  quadra- 
tus  lumborum  muscle,  where  it  divides  into  three  branches; 
one  of  which  goes  transversely  to  the  broad  muscles  of  the 
abdomen;  while  the  other  two  descend  between  the  oblique 
and  transverse  muscles  towards  the  crest  of  the  ilium,  where 
they  anastomose  with  the  lumbar  arteries,  and  with  the  cir- 
cumflexa  ilii. 


SECT.  V. OP  THE  BRANCHES  OP  THE  ABDOBIINAL  AORTA. 

The  Phrenic  Arteries  {Jirteriae  Phrenicx)  are  two  in 
number,  one  for  the  right  and  the  othet  for  the  left  side  of  the 
diaphragm.  They  arise  singly,  but  sometimes  by  a common 
trunk  from  the  front  of  the  aorta,  immediately  on  the  latter 
showing  itself  in  the  abdomen,  between  the  crura  of  the  dia- 
phragm; consequently  just  belowthecrossing  of  the  muscular 
fibres,  which  takes  place  between  the  foramen  for  the  aorta 
and  that  for  the  oesophagus. 


branches  of  the  abdominal  aorta. 


219 


The  phrenic  arteries  ascend  along  the  lesser  muscle  of  the 
diaphragm,  and  give  some  ramifications  to  it  and  to  the 
capsulae  renales.  They  then  divide  each  into  two  princi- 
pal trunks,  which  are  distributed  over  the  diaphragm,  prin- 
cipally on  its  concave  surface.  Some  small  ramifications 
from  them  go  to  the  liver  and  to  the  lower  part  of  the  oeso- 
phagus. 

The  two  pherenie  arteries  anastomose  with  each  other: 
also,  with  the  superior  phrenics,  coming  from  the  internal 
mammary;  and  with  the  intercostals.  Sometimes  one  or 
both  of  them  comes  from  the  coeliac  artery,  or  its  branches. 

The  Coeliac  Artery  {Jirteria  Coeliaca)  is  the  next  branch 
of  the  abdominal  aorta,  and  arises  immediately  below  the 
phrenic,  between  the  pillars  of  the  diaphragm,  opposite  the 
junction  of  the  last  dorsal  with  the  first  lumbar  vertebra. 
It  is  a very  large  trunk,  and  goes  off  at  right  angles,  being 
placed  between  the  left  lobe  of  the  liver  and  the  superior 
margin  of  the  pancreas.  When  it  is  only  half  an  inch  long 
it  is  split  into  three  trunks,  the  Gastric,  the  Hepatic,  and  the 
Splenic;  this  division  is  the  Tripus  Halleri. 

The  Gastric  Artery  [Jirteria  Gastrica,  Coronaria  Ven- 
triculi)  is  the  smallest  of  the  three  trunks,  and  frequently 
arises  from  one  of  the  others.  It  advances  forwards  and  to- 
wards the  left,  in  order  to  reach  the  small  curvature  of  the 
stomach,  the  course  of  which  it  pursues  to  the  pylorus,  be- 
tween the  two  laminae  of  the  little  omentum.  It  gives  off 
the  following  branches. 

a.  Ramifications  to  the  (esophagus,  some  of  which  as- 
cend along  it  into  the  posterior  mediastinum,  and  anasto- 
mose there  with  the  similar  branches  coming  from  the  aorta; 
others  go  transversely,  so  as  to  surround  the  cardia,  reach 
the  greater  end  of  the  stomach,  and  anastomose  with  the 
vasa  brevia. 

b.  The  ramifications  to  the  stomach  are  abundant,  but  of 
an  indeterminate  number,  and  arising  along  its  lesser  cur- 
vature, are  distributed  in  winding  branches  to  the  anterior 


CIKCULATORY  Sl'STKlM. 


220 

and  the  posterior  surfaces  of  tliis  viscus,  between  its  mem- 
branes. 

c.  Not  unfrequently  the  artery  which  supplies  the  left 
lobe  of  the  liver  is  a branch  from  the  gastric,  in  which  case 
the  latter  is  much  larger  than  usual. 

2.  The  Hepatic  Artery  {Jirteria  Hepatica)  is  generally 
considerably  larger  than  the  gastric,  and  inclines  towards 
the  right  side,  in  order  to  reach  the  liver,  which  it  does  , 
through  the  capsule  of  Glisson.  It  sends  off  the  following 
branches. 

a.  The  Right  Gastric  or  Gastro-Epiploic  Artery  {Arte- 
ria  Gastrica  Dextra)  comes  from  it  near  the  pylorus,  and 
descending  between  the  duodenum  and  pancreas,  reaches 
the  greater  curvature  of  the  stomach,  to  the  right  half  of 
which,  and  to  the  corresponding  part  of  the  great  omentum, 
it  is  distributed.  In  the  early  part  of  its  course,  the  right 
gastric  detaches  some  small  ramifications  to  the  pylorus 
[arterise  pyloricse;)  also,  to  the  duodenum  and  to  the  pan- 
creas {art.  pancreatico  duodenales.)  The  latter  commu- 
nicate, by  very  free  anastomoses,  with  the  superior  mesen-  ■ 
teric  artery.  , ^ 

After  having  sent  off  this  branch,  the  hepatic  artery  ad-  -ji 
vances  to  the  transverse  fissure  of  the  liver,  in  front  of  and  ' 
to  the  left  of  the  vena  portarum.  It  then  divides  into  a 
right  and  a left  branch.  The  former  sends  off  a ramifica- 
tion  to  the  gall  bladder,  {art.  Cystica,)  which  reaches  first 
its  neck  and  is  distributed,  by  many  arterioles,  upon  the  S 
parietes  of  this  reservoir;  the  right  branch  then  penetrates 
deeply  into  the  transverse  fissure,  and  is  distributed,  by  ' 
many  ramifications,  throughout  the  right  lobe  of  the  liver. 
The  left  branch  of  the  hepatic  artery  is  distributed,  in  the 
same  manner,  throughout  the  left  lobe  of  the  liver. 

3.  The  Splenic  Artery  {dlrteria  Splenica)  is  larger  in 
the  adult  than  either  of  the  other  two  branches  of  the  coeliac, 
and  goes  to  the  spleen  along  the  superior  margin  of  the 
pancreas,  performing,  in  this  course,  several  considerable  . 
flexuosities.  It  gives  off  the  following  branches: 


branches  of  the  abdominal  aorta. 


221 


a.  The  Pancreatic  Arteries  Pancreaticse  Medixef 

Sinistrae)  come  successively  from  its  inferior  margin,  as  it 
goes  along  the  pancreas.  Their  number  and  size  are  varia- 
ble, but  commonly  they  are  not  bigger  than  a knitting  nee- 
dle; they  penetrate  perpendicularly  into  the  pancreas,  and 
then  subdivide  minutely  in  furnishing  its  structure: 

b.  The  left  Gastric  Artery  {^rt,  Gastrica  Sinistra, 
Gastro-epiploica  Sinistra)  comes  from  the  left  extremity  of 
the  splenic,  and  is  about  the  same  size  with  the  right  gastric 
artery,  but  sometimes  larger.  It  attaches  itself  to  the  left 
extremity  of  the  stomach,  and  goes  along  the  left  half  of  its 
greater  curvature,  terminating  by  an  anastomosis  with  the 
right  gastric  artery.  In  this  course,  it  detaches  ramifica- 
tions to  the  front  and  to  the  back  of  the  stomach,  and  to  the 
omentum  majus: 

c.  The  Short  V essels  ( Vasa  Brevia,  Jirt.  Gastricse  Bre- 
ves) come  from  the  splenic,  immediately  before  it  enters 
the  spleen,  and  after  it  has  subdivided  for  that  purpose. 
They  are  five  or  six  in  number,  and  are  distributed  upon  the 
greater  extremity  of  the  stomach,  between  the  cardia  and 
the  left  gastric  artery.  The  anastomoses  between  the  se- 
veral arteries  of  the  stomach  are  so  free,  that  a fine  injec- 
tion pushed  into  one,  readily  finds  its  way  into  all  the 
others. 

The  splenic  artery,  when  it  gets  to  the  left  end  of  the 
pancreas,  is  divided  into  a cluster  of  branches,  and  in  that 
condition  enters  the  fissure  of  the  spleen,  throughout  the  in- 
terior of  which  it  is  divided  into  an  infinitude  of  ramifica- 
tions. 

The  Superior  Mesenteric  Artery  {tdrteria  Mesenterica 
Superior)  arises  from  the  aorta,  while  the  latter  is  still  en- 
gaged, between  the  crura  of  the  diaphragm.  It  is  about 
the  same  size  as  the  coeliac,  and  comes  ojBF  half  an  inch  be- 
low it.  It  is  distributed  to  all  the  small  intestine  and  to 
the  right  side  of  the  large  one  after  the  following  manner: 
it  first  passes  behind  the  pancreas,  and  then  in  front  of  the 
duodenum,  to  reach  the  root  of  the  mesenteiy,  between  the 


222 


CIRCULATORY  SYSTEM. 


two  laminae  of  which  it  divides  and  subdivides  into  several 
series  of  arches,  one  after  another;  they  become  successive- 
ly smaller  and  more  numerous  till  they  reach  the  margin 
of  the  intestine,  where  they  cease  by  sending  a great  many 
small  parallel  branches. 

The  trunk  of  the  superior  mesenteric  artery,  in  descend- 
ing between  the  laminae  of  the  mesentery,  describes  a con- 
siderable curvature,  the  convexity  of  which  is  to  the  left 
side  and  downwards,  while  its  concavity  is  in  a contrary 
direction.  It  is  from  the  convexity  of  this  trunk,  that 
from  fifteen  to  twenty  large  branches  are  sent  off  succes- 
sively to  form  the  roots  of  the  first  row  of  arterial  arches. 
These  branches  are  shorter,  and  generally  somewhat  smaller, 
the  lower  down  they  arise;  and  their  origins  very  closely 
succeed  each  other. 

Besides  the  preceding  branches,  the  superior  mesenteric 
artery  sends  off  the  following: 

Near  its  root  several  small  ramifications  arise,  which  go 
to  the  duodenum  and  to  the  pancreas,  and  anastomose  there 
with  other  arteries  supplying  the  same  organs: 

From  about  the  middle  of  the  concavity  of  the  superior 
mesenteric  artery,  arise  the  three  Colic  arteries  called  Ileo- 
colica,  Colica  Dextra,  and  Colica  Media:  the  first  supplies 
a cluster  of  branches  to  the  lower  part  of  the  ileum  and  to 
the  head  of  the  colon,  anastomosing  on  the  left  with  the 
last  of  the  small  intestinal  arteries  and  on  the  right  with 
the  colica  dextra:  the  Colica  Dextra  is  smaller  than  either 
of  the  other  two  branches,  and  going  between  the  laminae 
of  the  mesocolon,  supplies  the  ascending  portion  of  the  colon 
by  dividing  into  two  principal  branches,  one  of  which  anas- 
tomoses with  the  ileo-colic  artery,  and  the  other  with  the 
colica  media:  the  Colica  Media,  situated  between  the  la- 
minae of  the  ti’ansverse  mesocolon,  and  arising  higher  up 
than  the  colica  dextra,  advances  forwards  and  divides  into 
two  principal  trunks;  one  of  which  supplies  that  part  of 
the  colon  in  the  right  hypochondriac  region,  and  the  other 
the  remainder  of  its  transverse  portion,  forming  an  anasto- 
mosis with  the  colica  superior  of  the  inferior  mesenteric  ar- 


BRANCHES  OF  THE  ABDOMINAL  AORTA. 


223 


terv.  The  arteries  which  supply  the  colon  differ  from  those 
supplying  the  small  intestines,  in  forming  but  one  row  of 
arches;  which,  in  fact,  are  produced  by  the  anastomoses 
spoken  of,  and  have,  therefore,  extremely  large  meshes. 
From  the  convexity  of  these  arches,  many  parallel  branches 
run  out  to  supply  the  colon,  and  are  very  minutely  distri- 
buted to  it. 

The  Capsular  Arteries,  the  Emulgents,  and  the  Sperma- 
tics,  arise  from  the  aorta,  between  the  superior  and  the  in- 
ferior mesenteries.  But  they  will  be  described  after  the 
inferior  mesenteric,  so  as  to  keep  together  the  account  of 
the  arteries  of  the  intestines. 

The  Inferior  Mesenteric  Artery  Mesenterica  In- 

ferior) generally  arises  about  one  inch  above  the  division 
of  the  aorta  into  the  two  primitive  iliacs,  and  is  much 
smaller  than  the  superior  Mesenteric.  It  inclines  down- 
wards to  the  left  side,  and  gets  between  the  laminse  of  the 
mesocolon;  it  then  divides  into  three  branches,  called  the 
Left  Colic  Arteries,  from  their  distribution  to  the  left  side 
of  the  colon.  From  their  relative  situation  to  each  other 
they  are  distinguished  into  the  Superior,  the  Middle,  and 
the  Inferior;  sometimes  however  there  are  but  two  of  these 
trunks. 

The  Superior  Colic  {^^Irt.  Colica  Sinistra  Snpei'ior) 
goes  horizontally  towards  the  colon  in  the  left  lumbar  re- 
gion; having  got  near  the  intestine  it  divides  into  two 
branches,  one  of  which  ascends  to  the  transverse  colon  to 
form  the  anastomosis  with  the  Colica  Media  of  the  upper 
mesenteric,  while  the  other  descends  to  unite  with  the  colica 
media  sinistra.  The  middle  Colic  Artery  {^rt.  Colica  Si- 
nistra Media)  is  sometimes  a branch  of  the  superior,  and 
is  occasionally  wanting;  it  goes  towards  the  upper  part  of 
the  sigmoid  flexure  of  the  colon,  and  then  bifurcates;  one 
branch  ascends  to  form  by  anastomosis  an  arch  with  the  su- 
perior colic,  while  the  other  branch  descends  to  join  the 


224  CIRCULATORY  SYSTEM. 

lower  colic  artery.  The  Inferior  Colic  Artery  {Jirt.  Coli^ 
ca  Sinistra  Inferior)  goes  towards  the  middle  of  the  sig- 
moid flexure  of  the  colon,  and  there  like  the  preceding  di- 
vides into  two  branches;  one  anastomoses  with  the  artery 
above,  while  the  other  joins  with  the  arteries  which  go  to 
the  rectum  from  the  inferior  mesenteric. 

The  Superior  Hsemorrhoidal  Artery  {Art.  Hssmorrhoi- 
dea  Superior,  Interna)  is  the  lowest  and  the  last  branch  of 
the  inferior  mesenteric.  It  descends  between  the  laminje  of 
the  mesorectum,  and  is  divided  into  two  symmetrical 
trunks,  which  radiate  by  dividing  and  subdividing  on  the 
side  of  the  rectum,  and  are  dispersed  in  very  fine  and  nu- 
merous branches  throughout  its  substance;  and  anastomose 
with  the  middle  and  the  inferior  haemorrhoidal  arteries, 
also,  with  the  lateral  sacral. 

The  Capsular  Arteries  {Art.  Capsulares)  arise  frequent- 
ly from  the  aorta  just  below  the  superior  mesenteric;  but 
quite  as  often,  if  not  more  so,  from  the  emulgents.  They 
are  not  larger  than  a crow’s  quill,  and  vary  from  one  to 
three  on  either  side,  generally,  however,  not  exceeding 
one;  when  they  do,  they  are  proportionably  small.  Pass- 
ing horizontally  outwards  they  divide  into  several  small 
ramifications,  which  terminate  in  the  capsulse  renales, 
Some  of  their  branches  go  to  the  lesser  muscle  of  the  dia- 
phragm. 

The  Emulgent  Arteries  {Art.  Emulgentes  Renales)  are 
two  in  number,  one  for  each  kidney,  but  sometimes  more. 
They  are  large  and  short,  arise  from  the  side  of  the  aorta 
immediately  below  the  superior  mesenteric,  and  pass  out- 
wardly in  a horizontal  direction.  The  right  one  is  longer 
than  the  left,  somewhat  lower  down,  and  passes  behind  the 
ascending  cava.  They  are  both,  in  their  course  from  the 
aorta  to  the  kidney,  covered  in  from  by  the  emulgent  vein, 
and  have  to  pass  through  a mass  of  adipose  matter. 

The  emulgent  sends  off  some  fine  ramifications  to  the  adi- 
pose matter,  which  surrounds  it,  and  before  it  reaches  the 
fissure  of  the  kidney  divides  into  three  or  four  branches, 


BRANCHES  OF  THE  ABDOMINAL  AORTA.  225 

preparatory  to  its  introduction  into  this  gland;  upon  the 
structure  of  which  it  is  ultimately  distributed  by  very  fine 
branches. 

The  Spermatic-  Arteries  {Jirterix  Spermaticse,  Semi- 
nales)  arise  from  the  aorta  somewhat  below  the  emulgents, 
but  in  some  cases  from  the  latter  themselves.  They  are 
two  in  number,  one  on  each  side,  and  are  about  the  size  of 
a crow  quill  in  the  male  subject,  but  smaller  in  the  female. 
One  comes  off  generally  higher  up  than  the  other;  they 
then  descend  on  the  sides  of  the  vertebral  column  before 
the  psoas  muscles,  and  cross  in  front  of  the  ureters,  being  in 
all  this  course  behind  the  peritoneum.  They  are  tortuous, 
and  shortly  after  their  origin  begin  to  adhere  to  the  sper- 
matic veins,  which  adhesion  is  continued  to  the  testicle. 

The  branches  that  the  spermatic  artery  sends  off  in  the 
abdomen  are  inconsiderable,  consisting  in  very  fine  twigs 
to  the  adjacent  adipose  matter,  to  the  lymphatic  glands,  to 
the  ureter,  and  to  the  peritoneum.  In  the  male  subject 
it  passes  with  the  vas  deferens  through  the  abdominal  ca- 
nal, and  reaching  the  testicle  divides  into  branches  which 
supply  the  body  of  this  gland  and  the  epididymis.  In  de- 
scending from  the  external  ring  to  the  testis,  some  small 
ramifications,  to  the  adjacent  parts  leave  it.  In  the  female 
the  spermatic  artery  does  not  leave  the  cavity  of  the  abdo- 
men, but  descending  into  the  pelvis,  gets  between  the  la- 
minm  of  the  broad  ligament  to  the  ovavium,  and  is  spent 
principally  upon  the  latter.  Some  of  its  branches  go  to 
the  Fallopian  Tube,  to  the  Round  Ligament  of  the  uterus, 
and  to  the  sides  of  the  latter,  where  they  anastomose  with 
the  uterine  arteries. 

The  Lumbar  Arteries  [Arterise  Lumbares)  are  common- 
ly five  in  number  on  either  side,  but  seldom  less  than  three 
or  four,  and  in  their  course  outwards  correspond  with  the 
intercostal  arteries.  They  are  much  larger  than  the  latter. 
They  arise  in  pairs,  from  the  posterior  external  face  of  the 
aorta,  at  a point  corresponding  with  the  middle  of  the  bo- 
dies of  the  four  upper  lumbar  vertebra;  and  pass  outwards 

Voi.  IT. — 29 


22G 


CIRCULATORY  SYSTEM. 


between  the  fasciculi  of  the  psoas  magnus  muscle,  to  which, 
to  the  quadratus  lumborum,  and  the  bodies  of  the  vertebrae, 
they  distribute  several  branches.  Sometimes  each  pair 
arises  by  a common  trunk  from  the  posterior  face  of  the 
aorta;  as  the  latter  terminates  at  the  fourth  lumbar  verte- 
bra, the  fifth  lumbar  artery  is  a branch  from  the  fourth  in 
most  instances.  At  the  base  of  the  transverse  process  each 
artery  divides  into  two  branches,  a posterior  or  dorsal  one, 
and  an  anterior  or  lumbar. 

The  dorsal  branch,  which  is  smaller  than  the  other,  de- 
taches a ramification  though  the  intervertebral  foramen  to 
the  lower  part  of  the  medulla  spinalis  and  to  the  cauda  equi- 
na; it  then  gets  to  the  back  where  it  is  spent  upon  the  mus- 
cles near  the  spine.  The  anterior  lumbar  branch  advances 
between  the  broad  muscles  of  the  abdomen,  to  which  it  is 
distributed;  and  runs  forwards  far  enough  to  anastomose  with 
the  epigastric  artery. 

The  first  lumbar  artery  is  small,  and  sometimes  comes 
from  the  last  intercostal;  it  goes  a little  below  the  inferior 
margin  of  the  last  rib,  and  then  descends  almost  vertically 
between  the  peritoneum  and  the  transversus  abdominis 
muscle.  The  lower  lumbar  arteries  anastomose  with  the 
circumflexa  ilii,  and  with  the  superficial  branches  of  the 
gluteal. 

The  Middle  Sacral  Artery  {Jirteria  Sacra  Media)  is 
generally  not  so  large  as  a lumbar;  it  arises  from  the  centre 
of  the  bifurcation  of  the  aorta  into  the  two  primitive  iliacs, 
or  else  a line  or  two  above  it,  behind.  It  descends,  in  front 
of  the  middle  line  of  the  fifth  lumbar  vertebra  and  of  the 
sacrum,  to  the  coccyx,  adhering  to  the  surface  of  these 
bones  and  performing  some  flexuosities. 

It  sometimes  happens  that  the  last  pair  of  lumbar  arteries 
comes  from  it,  or  at  least  one,  according  to  Meckel,  more 
commonly  the  left,  in  which  case  the  sacral  is  of  unusual  size. ' 
The  sacral  afterwards  sends  off,  to  the  right  and  left,  a pair  of 
branches  for  each  pair  of  sacral  foramina.  They  run  across 
the  sacrum,  send  branches  to  it,  anastomose  with  the  late- 


INTERNAL  ILIAC  ARTERY  AND  ITS  BRANCHES.  227 

ral  sacral  arteries,  and  then  penetrate  to  the  cauda  equina. 
The  middle  sacral  artery  is  lost  at  the  inferior  end  of  the 
coccyx,  in  the  fat  and  cellular  tissue  of  the  part. 

SECT.  VI. OF  THE  PRIMITIVE  ILIAC  ARTERY  AND  ITS 

BRANCHES. 

The  Primitive  Iliac  Arteries,  («/2r#.  Iliacse  Primitivae, 
communes,)  one  on  each  side,  are  as  mentioned,  the  ter- 
minating trunks  of  the  abdominal  aorta.  They  extend 
from  the  lower  part  of  the  fourth  lumbar  vertebra  to  the 
sacro-iliac  junction  or  near  it,  where  they  divide  into  two 
trunks,  the  Internal  and  the  External  Iliac. 

The  primitive  Iliac  is  bounded  on  the  outer  side  by  the 
psoas  magnus  muscle,  and  behind  by  the  primitive  iliac 
vein;  it  is  crossed  at  its  lower  part  b}'-  the  ureter.  No 
branches  deserving  of  especial  notice  are  sent  from  it  before 
it  bifurcates;  such  as  exist  are  very  small,  and  go  simply  to 
the  parts  immediately  contiguous.  The  right  artery 
crosses  in  front  of  the  root  of  the  left  iliac  vein. 

SECT.  VII.^OF  THE  INTERNAL  ILIAC  ARTERY  AND  ITS 
BRANCHES. 

The  Internal  Iliac  Artery  {Jlrt.  Iliaca  Interna,  Hypogas- 
trica)  descends  from  the  front  upper  part  of  the  sacro-iliac 
junction,  to  the  lower  part  of  the  sacro-iliac  junction. 
In  this  descent,  it  is  bounded  behind  by  the  sacral  plexus  of 
nerves,  and  gives  olF  several  arterial  trunks,  but  the  man- 
ner by  which  the  last  is  accomplished  is  much  varied  in  dif- 
ferent subjects.  For  the  most  part,  it  is  an  inch  or  more 
long  before  any  important  branches  leave  it;  it  is  then  fre- 
quently divided  into  two  principal  trunks,  an  anterior  and 
a posterior,  from  which  proceed  the  several  branches  that 
supply  the  internal  and  the  external  parts  of  the  pelvis. 
The  rule  of  origin  of  the  secondary  trunks  from  these  two 
principal  ones,  even  when  the  latter  exist,  is  not  fixed,  for 


228. 


CIRCULATORY  SYSTEM. 


sometimes  they  arise  from  one,  sometimes  from  the  other, 
and  then  again  from  the  trunk  of  the  hypogastric  itself. 

The  Ilio-Lumbar  Artery  {Jirt.  Ilio-lumbaris)  is  com- 
monly the  first  branch  of  the  hypogastric  or  of  its  posterior 
trunk.  It  ascends  outwards  and  backwards  behind  the  psoas 
magnus  muscle,  and  there  divides  into  two  branches,  a su- 
perior and  an  inferior.  The  former  continues  to  ascend  be- 
tween the  psoas  magnus  and  the  iliaeus  ipternus  muscles, 
to  which,  and  to  the  quadratus  lumborum,  it  distributes 
branches;  it  also  sends  ramifications  into  the  spinal  cavity, 
and  anastomoses  with  the  lower  lumbar  arteries;  sometimes 
it  supplies  the  place  of  the  last  lumbar  entirely.  The  infe- 
rior branch  going  outwardly  is  divided  into  two  orders  of 
ramifications  which  supply  the  iliaeus  internus  muscle,  on 
its  surface  and  more  deeply,  also  the  os  ilium  by  a ramus- 
cle  which  penetrates  the  nutritious  foramen  of  the  latter. 
The  inferior  branch  anastomoses  with  the  circumflexa  ilii 
of  the  external  iliac. 

The  Lateral  Sacral  Arteries  {Jirterias  Sacrae  Laterales) 
arise  next,  either  from  the  hypogastric  or  from  its  posterior 
trunk,  their  number  is  commonly  equal  to  that  of  the  fora- 
mina on  the  side  of  the  sacrum  in  front,  though  they  come 
from  only  one  or  two  roots.  They  cross  the  front  of  th^ 
sacrum  and  divide  into  branches,  some  of  which  anastomose 
with  the  middle  sacral  artery,  while  others  enter  the  fora- 
mina of  the  sacrum,  to  be  spent  on  the  lower  part  of  the 
cauda  equina. 

The  Obturator  Artery  {tfirteria  Ohturatoria)  comes  com- 
monly from  the  hypogastric  or  from  one  of  its  principal 
trunks;  in  some  cases  it  arises  from  the  epigastric  or  from 
the  external  iliac,  near  Poupart’s  ligament.  In  the  first 
cases  it  passes  forwards  parallel  with  the  brim  of  the  pel- 
vis, and  in  the  latter  cases  it  descends  behind  the  superior 
ramus  of  the  pubes.  Whatever  may  be  the  condition  of 
its  origin,  it  gets  from  the  pelvis  j^through  the  upper  part  of 


INTERNAL  ILIAC  ARTERY  AND  ITS  BRANCHES.  229 

the  thyroid  foramen  over  the  superior  margin  of  the  obtu- 
rator internus  muscle,  having  previously  sent  off  some  in- 
considerable ramifications  to  the  periosteum  and  the  conti- 
guous muscles. 

It  emerges  from  the  pelvis  on  the  upper  margin  of  the  ob- 
turator externus  muscle,  and  then  divides  into  two  principal 
trunks.  The  posterior  descends  along  the  external  margin 
of  the  obturator  externus  muscle,  to  which  it  gives  ramifi- 
cations; it  likewise  sends  s5me  branches  to  the  heads  of  the 
muscles  coming  from  the  tuber  of  the  ischium  and  thereby 
anastomoses  with  the  sciatic  artery;  other  branches  ai'e 
spent  upon  the  hip  joint,  one  of  which  gets  into  the  cavity 
of  the  latter  through  the  notch  at  the  lower  part  of  the  ace- 
tabulum, and  is  spent  upon  the  adipose  matter  in  its  bottom. 
The  anterior  branch  goes  to  the  heads  of  the  adductor  mus- 
cles, to  the  pectineus,  to  the  obturator  externus,  and  to  the 
integuments  of  the  upper  internal  part  of  the  thigh.  Near 
its  origin  this  branch  sends  a ramification  along  the  internal 
margin  of  the  thyroid  foramen  to  anastomose  with  the  pos- 
terior bi’anch,  so  that  the  foramen  is  surrounded  by  an  ar- 
terial circle. 

The  Middle  Haemorrhoidal  Artery  Hsemorrhoidea 
Media)  varies  in  its  origin,  being  sometimes  from  the  hy- 
pogastric itself,  and,  on  other  occasions,  from  one  of  its 
branches,  as  the  gluteal,  ischiatic,  &c.  It  descends  on  the 
fore  part  of  the  rectum,  opposite  the  lower  fundus  of  the 
bladder  in  the  male,  and  is  distributed  by  branches  to  the 
rectum,  to  the  vesiculse  seminales,  and  to  the  prostate 
gland.  In  the  female  it  dispenses  branches  to  the  vagina. 
It  is  called  middle  from  its  position  between  the  upper  and 
the  lower  haemorrhoidal  arteries. 

In  both  sexes  the  branches  which  it  sends  to  other  parts 
besides  the  rectum,  frequently  arise  from  other  arteries,  and 
in  a manner  which  causes  them  to  have  distinct  appellations, 
as  vaginal,  &c. 

The  Vesical  Arteries  {Arterise  Vesicales)  consist  in  se- 


230 


CIKCUX.ATORY  SYSTEM. 


veral  ramifications,  coming  from  what  was  the  umbilical  ar- 
tery of  the  foetus,  but  which,  in  the  adult,  with  the  excep- 
tion of  a short  space  near  its  origin,  is  converted  into  a li- 
gamentous chord.  These  branches  ramify  upon  the  parietes 
of  the  bladder;  one  of  them  more  voluminous  than  any 
other,  and  called  by  M.  Chaussier,  vesico-prostatic,  gains 
the  lower  fundus  of  the  bladder;  sends  branches  to  it,  to 
the  prostate,  to  the  vesiculae  seminales,  and  to  the  com- 
mencement o(  the  urethra. 

The  Uterine  Artery  {Jirteria  Uterina)  arises  from  the 
hypogastric  or  one  of  its  branches,  near  the  vesicals,  some- 
times before,  and  on  other  occasions  subsequent  to  them. 
Being  peculiar  to  the  female  sex,  its  size  varies  according 
to  the  individual,  being  in  a state  of  pregnancy  or  not;  in 
the  latter  stages  of  gestation  it  is  as  large  as  any  other 
branch  of  the  hypogastric. 

It  goes  inwards  towards  the  superior  part  of  the  vagina,  to 
which  it  gives  some  ramifications;  it  then  ascends  between 
the  laminae  of  the  broad  ligament,  in  a tortuous  manner 
along  the  side  of  the  uterus,  and  divides  into  many  branches 
which  are  distributed  through  the  tissue  of  this  organ.  It 
anastomoses  with  the  corresponding  arteries  of  the  other 
side,  and  with  the  branches  of  the  spermatic  artery  which 
go  to  the  Fallopian  tube  and  to  the  ovarium. 

Besides  the  preceding,  the  hypogastric  arteiy  sends  off 
two  large  branches,  the  Gluteal  and  the  Ischiatic,  which  ter- 
minate it.  In  many  subjects  they  are  the  direct  continua- 
tion of  the  two  primitive  trunks,  into  which  the  hypogas- 
tric is  frequently  originally  divided. 

The  Gluteal  Artery  {Jirteria  Glutea)  shortly  after  its 
origin,  issues  from  the  pelvis  above  the  pyriformis  muscle, 
at  the  upper  part  of  the  ischiatic  foramen,  where  it  adheres 
closely  to  the  edge  of  the  bone.  When  it  first  gets  to  the 
dorsum  of  the  ilium,  it  is  covered  by  the  gluteus  maximus 
muscle,  and  lies  at  the  posterior  margin  of  the  gluteus  mi- 


IKTEBNAL  ILIAC  ARTERV  AND  ITS  BRANCHES.  231 

nimus,  precisely  under  a line  drawn  from  the  posterior  su- 
perior spinous  process  to  the  top  of  the  trochanter  major. 
It  almost  immediately  afterwards  divides  into  two  principal 
trunks. 

One  of  these  trunks,  the  more  superficial,  advances  be- 
tween the  gluteus  medius  and  the  maximus,  and  distributes 
branches  to  them;  also,  to  the  posterior  margin  of  the  max- 
imus, where  it  eomes  from  the  posterior  sacro-sciatic  liga- 
ment. The  more  deeply  seated  trunk  goes  forwards  be- 
tween the  gluteus  medius  and  minimus,  and  subdivides  into 
three  orders  of  branches  for  their  supply.  One  set  follows 
the  superior  margin  of  the  gluteus  minimus  towards  the 
anterior  superior  spinous  process;  another  set  passes  nearer 
the  middle  of  the  gluteus  minimus;  and  the  third  set  still 
lower  down,  upon  the  dorsum  of  the  ilium,  above  the  ace- 
tabulum; some  of  the  ramifications  going  to  the  capsular  li- 
gament of  the  joint,  where  they  anastomose  with  branches 
from  the  femoral  arter}''. 

The  Ischiatic  Artery  (^Arteria  Ischiadica)  is  somewhat 
smaller  than  the  gluteal,  but  looks  rather  moi-e  like  the  con- 
tinuation of  the  hypogastric.  It  descends  between  the  rec- 
tum and  the  pyriformis  muscle,  and  issues  under  the  lower 
margin  of  the  latter,  out  of  the  pelvis,  being  there  placed 
in  front  of  the  sciatic  nerve.  It  goes  downwards  on  the 
back  of  the  thigh,  between  the  trochanter  major  and  the 
tuberosity  of  the  ischium,  being  at  the  internal  edge  of  the 
sciatic  nerve,  and  on  the  posterior  face  of  the  small  rotator 
muscles  of  the  thigh.  It  sends  off  in  the  pelvis  the  Inter- 
nal Pudic  Artery,  and  also  some  inconstant  branches,  of 
small  size,  to  the  viscera  within  the  pelvis;  when  it  has 
emerged  from  the  latter,  it  detaches  some  considerable 
branches  to  the  origin  and  to  the  inferior  margin  of  the  glu- 
teus magnus  muscle,  and  to  the  small  rotator  muscles.  The 
branch  which  may  be  considered  as  the  continued  trunk  of 
the  ischiatic,  descending  on  the  posterior  face  of  the  thigh, 
along  with  the  sciatic  nerve,  under  the  hamstring  muscles. 


CIRCULATORY  SYSTEM. 


is  lost  in  ramifications  to  them,  and  by  anastomoses  witii 
the  perforating  arteries. 

The  Internal  Pudic  Artery,  {Arteria  Pudica  Interna,) 
though  a branch  of  the  ischiatic,  is  only  in  a slight  degree 
smaller.  It  arises  a little  above  the  spinous  process  of  the 
ischium,  in  the  pelvis,  in  front  of  the  sciatic  plexus,  and 
getting  from  the  pelvis  between  the  anterior  sacro-sciatic 
ligament  and  the  inferior  margin  of  the  pyriformis  muscle, 
it  passes  over  the  posterior  face  of  the  anterior  sacro-sciatic 
ligament,  at  the  spinous  process  of  the  ischium.  It  imme- 
diately afterwards  returns  into  the  cavity  of  the  pelvis,  be- 
tween the  two  sacro-sciatic  ligaments,  at  the  place  where 
the  obturator  internus  muscle  winds  over  the  ischium;  it 
then  winds  along  the  internal  face  of  the  latter  bone  and  of 
its  ascending  ramus,  at  the  inferior  margin  of  the  obturator 
internus  muscle;  and  continues  on  the  internal  face  of  the 
ramus  of  the  pubes,  between  the  two  laminae  of  the  trian- 
gular ligament,  above  the  crus  of  the  penis  to  the  symphy- 
sis of  the  pubes. 

In  this  course  the  Internal  Pudic  Artery  detaches  seve- 
ral important  branches,  in  the  following  order: 

a.  A ramification  along  the  inferior  margin  of  the  pyri- 
formis, to  this  muscle  and  to  the  parts  on  the  posterior  face 
of  the  neck  of  the  os  femoris,  where  it  anastomoses  with 
the  other  arteries  of  this  region.  ' ' 

h.  The  Lower  Hsemorrhoidal  Artery  {Art.  Hsemor- 
rhoidea  Inferior  Externa)  to  the  inferior  part  of  the  rec- 
tum, and  to  the  sphincter  ani  muscle.  This  artery  arises 
after  the  internal  pudic  has  returned  within  the  pelvis,  and 
consists  sometimes  in  several  branches. 

c.  The  Perineal  Artery  [Art.  Perinea,  Transversa  Pe- 
rinei)  has  its  root  near  the  origin  of  the  transversus  peri- 
nei  muscle,  and  advancing  obliquely  forwards  is  distributed 
in  several  ramifications  to  the  muscles  and  integuments  of 
the  perineum,  and  to  the  posterior  part  of  the  scrotum.  It 
is  unavoidably  cut  in  the  lateral  operation  for  the  stone.  In 
the  female  it  goes  to  the  sphincter  vaginae  and  to  the  labi- 
um externum. 


EXTERNAL  ILIAC  ARTERf  AND  ITS  BRANCHES.  233 

d.  When  the  internal  pudic  has  got  beyond  the  transver- 
sus  perjnei  muscle  near  the  beginning  of  the  crus  penis,  it 
detaches,  to  the  bulb  of  the  urethra,  along  the  posterior 
margin  of  the  triangular  ligament,  a branch  which  pene- 
trates to  the  corpus  spongiosum,  and  is  minutely  distributed 
upon  it,  some  of  its  ramifications  reaching  to  the  corpus 
cavernosum.  This  branch  is  called  by  M,  Chaussier  Ure- 
thro-bulbar,  and  instead  of  being  always  distinct,  it  on  some 
occasions  comes  from  the  Perineal. 

e.  At  the  under  part  of  the  symphysis  pubis,  between  it 
and  the  back  of  the  penis,,  the  internal  pudic  sends  for- 
wards, on  the  dorsum  of  the  penis,  a superficial  branch 
{Ramus  Superficialis  Dorsi  Penis.)  It  advances  to  the 
end  of  the  penis,  under  the  skin,  being  parallel  with  its 
fellow  of  the  other  side,  and  near  to  it;  sometimes  the  two 
unite  after  a short  course.  They  are  dispersed  in  branches 
to  the  integuments,  and  to  the  elastic  ligament  of  the  penis. 

f.  The  Cavernous  Artery  of  the  Penis  {Jirt.  Cavernosa 
Profunda  Penis)  may  be  considered  as  the  terminating- 
trunk  of  the  internal  pudic.  It  penetrates  the  corpus  ca- 
vernosum, beneath  the  symphysis  of  the  pubes,  and  quick- 
ly divides  into  many  ramifications.  The  latter  advance, 
and  continue  to  subdivide  upon  the  cells  of  the  corpus  ca- 
vernosum, to  which  they  are  principally  distributed;  some 
of  them  reach  the  corpus  spongiosum  urethrae,  and  others 
anastomose  with  the  corresponding  arteries  of  the  other 
side. 

SECT.  VIII. OE  THE  EXTERNAL  ILIAC  ARTERV  AND  ITS 

BRANCHES. 

The  External  Iliac  Artery  {Jirteria  Iliaca  Externa) 
extends  from  the  bifurcation  of  the  primitive  iliac  to  Pou- 
part’s  Ligament,  where  it  is  continued  to  the  lower  extre- 
mity under  the  name  of  the  femoral  artery.  It  looks  like 
the  continuation  of  the  primitive  iliac,  and  descends  at  the 
superior  strait  of  the  pelvis  along  the  internal  margin  of  the 

VoL.  II. — 30 


CIUOULATOKV'  Si'STEM. 


psoas  magnus  muscle.  In  the  early  part  of  its  course,  it  is 
anterior  to  the  external  iliac  vein;  it  then,  as  it  approaches 
Poupart’s  ligament,  gets  to  its  outer  margin.  It  is  covered 
by  the  peritoneum  in  front.  Where  it  passes  beneath  Pou- 
part’s ligament  to  the  thigh,  it  is  about  half  way  between 
the  anterior  superior  spinous  process  of  the  ilium  and  the 
symphysis  pubis,  having  the  vein  at  its  pubic  margin  and 
the  anterior  crural  nerve,  half  an  inch  from  its  iliac  margin. 
No  branches  of  consequence  arise  before  it  reaches  the  cru- 
ral arch;  it  then  sends  off  two,  the  Epigastric  and  the  Cir- 
cumflex of  the  Ilium. 

The  Epigastric  Artery  {Jirttria  Epigastrica)  arises 
somewhat  above  the  crural  arch,  at  the  line  where  the  pe- 
ritoneum is  reflected  from  the  fascia  transversalis  upon  the 
iliac  fascia.  It  at  first  passes  horizontally  inwards,  then 
rises  obliquely  upwards  and  inwards,  behind  the  sperma- 
tic chord,  at  the  pubic  margin  of  the  internal  abdominal 
ring.  Afterwards  it  reaches  the  external  margin  of  the  rec- 
tus abdominis  muscle,  two  or  three  inches  above  the  pubes; 
ascending  along  it  for  a short  distance,  it  then  passes  to  its 
posterior  face,  and  continues  ascending  above  the  umbi- 
licus; where  being  divided  into  several  branches,  it  termi- 
nates by  anastomosing  with  the  lower  ramifications  of  the 
internal  mammary  artery. 

This  artery  is  almost  entirely  spent  upon  the  anterior  pa- 
rietes  of  the  abdomen,  in  ramifications,  which  anastomose 
with  the  last  intercostal  and  with  the  lumbar  arteries.  One 
of  its  small  twigs,  following  the  course  of  the  spermatic 
chord,  or  of  the  round  ligament,  is  distributed  upon  the 
cremaster,  the  tunica  vaginalis,  and  the  scrotum  of  the 
male,  and  upon  the  mons  veneris  of  the  female.  In  some 
cases  it  gives  off  the  obturator  artery. 

The  Circumflex  Artery  {Jirteria  Circumjlexa  Ilii)  is  of 
the  same  size  with  the  epigastric,  and  comes  from  the  ex- 
ternal iliac,  sometimes  on  a level  with  it,  and  on  other  oc- 
casions lower  down,  even  below  the  crural  arch.  It  as- 


TEMORAL  ARTERY. 


235 


eends  outwardly  towards  the  anterior  superior  spinous  pro- 
cess of  the  ilium,  along  the  posterior  margin  of  the  crural 
arch,  and  following  afterwards  the  direction  of  the  crista  of 
the  ilium,  it  anastomoses  with  the  corresponding  branch  of 
the  ilio-lumbar  artery. 

The  following  branches  come  from  it.  In  the  early  part 
of  its  course  some  unimportant  twigs  are  sent  to  the  adja- 
cent muscles,  as  the  sartorius,  iliacus  internus,  and  so  on. 
At  the  anterior  superior  spinous  process  it  divides  into  two 
branches,  the  smaller  ascends  between  the  internal  oblique 
and  the  transversalis  muscle,  and  is  distributed  upon  them; 
the  other  branch,  which  is  the  continuation  of  the  main 
trunk  along  the  crista  of  the  ilium  at  the  margin  of  the 
iliacus  internus  muscle,  sends  ramifications  to  the  latter, 
and  also  to  the  posterior  part  of  the  broad  muscles  of  the 
abdomen,  where  it  anastomoses  with  the  other  arteries  of 
this  region. 

Of  the  Femoral  Artery. 

The  Femoral  Artery  {Arteria  Femoralis,  Cruralis)  the 
continuation  of  the  external  iliac  extends  from  the  crural 
arch  to  the  perforation  for  its  passage  through  the  adductor 
magnus,  which  is  commonly  one-third  of  the  whole  length 
of  the  os  femoris,  above  the  knee  joint.  This  great  trunk, 
immediately  below  Poupart’s  ligament  is  very  superficial,  and 
may  be  felt  pulsating  whex'e  it  passes  over  the  pubes.  It  is 
there  covered  only  by  the  common  integuments  and  the  fas- 
cia femoris,  which  is  thin;  it  is  bounded  internally  by  the 
femoral  vein,  externally  by  the  crural  nerve,  is  half  way  be- 
tween the  anterior  superior  spinous  process  and  the  sym- 
physis of  the  pubes,  and  lies  upon  the  internal  face  of  the 
psoas  magnus  over  the  interstice  between  it  and  the  pecti- 
neus.  In  the  upper  third  of  its  course  the  femoral  arter}>- 
IS  at  the  inner  edge  of  the  rectus  femoris,  and  at  a short 
distance  from  it;  it  then  inclines  inwards,  and  occupies  the 
angle  formed  by  the  adhesion  of  the  vastus  internus  to  the 
adductor  longus.  The  sartorius,  at  first,  is  remote  at  its 


236 


CIRCULATORV  SYSTEM. 


outside,  but  this  muscle  inclining  inwards  in  its  descent  gets 
to  the  exterior  margin  of  the  artery,  and  afterwards  covers 
it  completely  for  the  remainder  of  its  course.  The  femo- 
ral artery  is  in  front  of  the  femoral  vein  when  it  has  des- 
cended three  or  four  inches  below  the  crural  arch;  behind 
the  two  is  the  arteria  profunda.  When  the  femoral  ai’tery 
and  vein  reach  the  angle  formed  by  the  vastus  internus  and 
the  adductor  longus,  they  are  .covered  by  a strong  inter- 
lacement of  tendinous  fibres  from  these  muscles. 

The  femoral  artery  sends  off  these  branches: 

1.  The  Superficial  Artery  of  the  Abdomen  ad  Cu- 

tem  Jihdominis)  is  small,  and  arises  at  the  lower  margin 
of  Poupart’s  ligament;  it  goes  upwards  towards  the  umbi- 
licus, lies  beneath  the  fascia  superficialis  abdominis,  and  is 
distributed  to  the  integuments  of  this  region.  One  of  its 
ramifications  goes  to  the  inguinal  glands. 

2.  The  External  Pudic  Arteries  [Jirt.  Pudendse  Ex- 
ternse)  come  from  the  femoral  at  the  same  point,  and  are 
two  or  even  three  in  number,  they  are  of  small  size.  One 
of  them  inclines  inwards  along  the  groin,  between  the  skin 
and  the  fascia  femoris,  and  is  distributed  to  the  integu- 
ments of  the  pubes — to  those  of  the  penis, — and  to  the 
scrotum,  or  to  the  labium  externum  of  the  female.  The 
second,  and  the  third  when  it  exists,  are  rather  lower  down, 
and  are  dispersed  upon  very  much  the  same  parts.  The 
lymphatic  glands  of  the  groin  also  derive  their  supply  of 
blood  from  these  external  pudic  arteries. 

3.  The  Profound  Artery,  {Arteria  Profunda  Femoris) 
the  great  muscular  artery  of  the  thigh,  is  but  slightly  infe- 
rior in  size  to  the  femoral  itself,  and  comes  from  the  latter 
at  the  distance  of  from  one  to  two  inches  below  the  crural 
arch.  It  lies  behind  the  femoral  artery,  and  descends  in 
that  situation  between  the  insertion  of  the  adductor  brevis 
and  the  vastus  internus  muscle,  to  the  upper  part  of  the  in- 
sertion of  the  adductor  longus.  In  this  course  its  size  is 


PROFOUND  ARTERY. 


237 


much  diminished,  by  the  origin  from  it  of  several  conside- 
rable trunks,  as  follows: 

a.  The  External  Circumflex  {Jirteria  Circumjlexa  Ex- 
terna) though  most  frequently  a branch  of  the  profunda, 
sometimes  comes  from  the  femoral  above  or  below  it  a short 
distance.  It  goes  immediately  outwards  between  the  rectus 
femoris  muscle  and  the  cruralis,  giving  off  some  inconside- 
rable ramifications.  While  between  these  muscles  it  divides 
into  two  branches,  one  of  which  ascends,  and  the  other 
descends;  the  former  is  distributed  to  the  anterior  margins 
of  the  gluteus  medius  and  minimus,  to  the  capsule  of  the 
joint,  and  the  parts  about  the  trochanter  major,  anasto- 
mosing with  the  gluteal  and  the  ischiatic.  It  is  said  by 
Meckel,  that  these  anastomoses  have  been  found  much  di- 
lated where  the  external  iliac  artery  has  been  taken  up. 
The  descending  branch  is  about  the  size  of  a crow  quill, 
or  even  larger;  it  first  passes  obliquely  downwards  between 
the  rectus  femoris  and  the  cruralis,  it  then  descends  verti- 
cally under  the  anterior  margin  of  the  vastus  externus  be- 
tween it  and  the  cruralis,  to  terminate  at  the  knee,  where 
it  becomes  superficial  and  anastomoses  with  the  articular  ar- 
teries. It  is,  however,  principally  distributed  to  the  vastus 
externus  and  to  the  cruralis. 

b.  The  Internal  Circumflex  Artery  {Jirteria  Circum- 
jlexa Interna)  arises  from  the  profunda,  near  the  external 
circumflex,  generally  below  it,  but  sometimes  the  reverse; 
'in  some  cases,  it  comes  from  the  femoral  artery  itself,  near 
the  crural  arch.  It  passes  transversely  inwards,  and  dips 
into  the  interstice  between  the  pectineus  and  the  psoas  mag- 
nus,  after  having  given  off  some  small  twigs  to  the  heads 
of  the  adjoining  adductors.  It  then  winds  under  the  neck 
of  the  os  femoris  and  divides  into  two  branches;  the  upper 
one  goes  to  the  capsular  ligament  of  t'.je  joint,  to  the  obtu- 
rator externus  muscle,  anastomoses  with  the  obturator  ar- 
tery, and  sends  a branch  behind  the  adductor  brevis  to  the 
upper  part  of  the  adductor  magnus;  the  inferior  branch 
is  larger  than  the  other,  it  descends  behind  the  adductor 
magnus  and  is  distributed  in  branches  to  it,  to  the  gracilis, 


J 


23S 


CIRCULATORY  SYSTEM. 


and  to  the  liamstring  muscles,  sending  upwards  some  rami- 
fications (rami  trochanterici)  to  the  parts  about  the  trochan- 
ter major,  where  they  anastomose  with  the  external  circum- 
flex artery. 

c.  Muscular  branches  of  inconstant  origin,  and  of  incon- 
siderable size,  are  sent  from  the  profunda  to  supply  the  an- 
terior face  of  the  adductor  muscles. 

d.  The  Perforating  Arteries  {Rami  Profundi  Perforan- 
ies)  obtain  the  name  from  their  perforating  the  adductor 
magnus,  which  they  do  near  the  linea  aspera,  so  as  to  get 
to  the  back  of  the  thigh.  They  commonly  are  four  in  num- 
ber, and  as  they  come  off  successively  from  the  profunda, 
they  are  designated  numerically.  In  some  cases,  however, 
they  are  reduced  to  one,  by  being  concentrated  in  a com- 
mon trunk,  which,  penetrating  high  up  the  adductor  mag- 
nus, and  afterwards  descending  on  its  posterior  face,  is  dis- 
persed upon  the  muscles  on  the  back  of  the  thigh. 

The  First  Perforating  Artery  arises  somewhat  below  the 
trochanter  minor,  and  penetrates  the  adductor  magnus  a lit- 
tle below  its  superior  margin.  One  of  its  branches  ascends 
towards  the  trochanter  major,  where  it  anastomoses  with 
the  external  circumflex  and  with  the  gluteal,  while  another 
descending  is  spent  upon  the  heads  of  the  flexor  muscles  of 
the  leg. 

The  Second  Perforating  Artery  gets  to  the  back  of  the 
thigh,  at  the  lower  margin  of  the  insertion  of  the  gluteus 
maximus  into  the  linea  aspera,  being  distributed  in  that  re- 
gion and  to  the  corresponding  portion  of  the  long  head  of 
the  liiceps  flexor  cruris. 

The  Third  Perforating  Artery  penetrates  the  adductor 
magnus  somewhat  below  the  commencement  of  the  short 
head  of  the  biceps,  and  is  dispersed  upon  the  adductor  and 
the  adjacent  portion  of  the  flexor  muscles. 

The  Fourth  Perforating  Artery  penetrates  the  insertion 
of  the  adductor  magnus  an  inch  and  a half  above  the  open- 
ing in  it,  for  the  femoral  artery;  it,  in  the  same  way,  sup- 
plies the  posterior  face  of  the  adductor  and  the  adjacent 
muscles. 


POPLITEAL  AKTERy. 


239 


As  a summary,  it  will  be  readily  understood  that  the  pro- 
funda is,  in  this  way,  through  the  external  and  the  internal 
circumflex,  and  through  the  perforating  arteries,  distributed 
upon  all  the  large  muscles  of  the  thigh. 

After  the  origin  of  the  profunda,  the  Femoral  Artery 
gives  off,  at  different  points  of  its  course  to  the  opening  of 
the  adductor  magnus,  several  twigs,  the  size  of  a large  knit- 
ting needle,  which  go  to  the  sartorius,  the  gracilis,  the  ad- 
ductors, and  the  extensors  on  the  front  of  the  thigh j but 
they  are  too  inconstant  to  require  more  particular  descrip- 
tion. 

The  Anastomosing  Artery  [Jlrteria  ^dnastomotica)  is 
the  last  branch  of  the  femoral,  and  arises  just  before  it  perfo- 
rates the  adductor  magnus.  It  descends  to  the  knee  in  front 
of  the  tendon  of  the  latter,  concealed  by  the  internal  mar- 
gins of  the  vastus  internus  muscle.  It  sends  off  many  small 
twigs  to  the  adjacent  muscles,  and  terminates  below  by 
anastomosing  with  the  internal  articular  arteries.  It  is 
about  the  size  of  a crow  quill. 

The  Popliteal  Artery  (Arteria  Poplitsea)  is  the  conti- 
nuation of  the  femoral,  after  the  latter  has  passed  through 
the  tendinous  insertion  of  the  adductor  magnus,  and  ex- 
tends from  this  point  to  the  opening  in  the  interosseous  li- 
gament of  the  leg,  just  below  the  head  of  the  tibia.  It  first 
of  all  passes  from  tbe  internal  margin  of  the  os  femoris,  to 
the  notch  between  the  condyles,  being  there  placed  in  the 
middle  between  the  internal  and  the  external  hamstring 
muscles,  and  surrounded  by  a mass  of  adipose  matter  which 
fills  up  the  hollow  of  the  ham.  It  is  in  contact,  anteriorly, 
with  the  knee  joint,  and  a little  below  the  latter  with  the 
popliteus  muscle,  descending  there  between  the  heads  of  the 
gastrocnemius.  It  is  covered  in  the  greater  part  of  its  ex- 
tent, posteriorly,  by  the  popliteal  vein  and  by  the  sciatic 
nerve,  the  latter  being  more  superficial  than  the  vein. 

The  popliteal  artery  sends  off  some  small  branches  to  the 
hamstring  muscles  and  to  the  parts  contained  between  the 


240 


CIKCULATORy  SYSTEM. 


latter,  which  are  too  irregular  and  inconstant  for  descrip- 
tion. The  following  arteries  also  come  from  it: 

1.  The  Superior  Internal  Articular  Artery  {.Art.  Articu- 
laris  Superior  Interna)  arises  at  or  above  the  internal  con- 
dyle, and  frequently  consists  in  two  trunks.  It  passes 
through  the  tendon  of  the  adductor  magnus,  just  above  the 
condyle;  it  then  begins  to  distribute  itself  in  branches,  some 
of  which  are  spent  upon  the  lower  part  of  the  vastus  internus 
muscle,  and  others  upon  the  superior  internal  part  of  the 
knee  joint. 

2.  The  Superior  External  Articulating  Artery  {Art.  Ar- 
ticularis  Superior  Externa)  arises  from  the  popliteal, 
somewhat  above  the  external  condyle  of  the  os  femoris.  It 
winds  horizontally,  above  the  external  condyle,  around  the 
bone,  between  it  and  the  lower  part  of  the  biceps  flexor 
cruris,  and  is  then  distributed  also  In  two  orders  of  branches, 
some  of  which  supply  the  lower  part  of  the  vastus  externus 
muscle,  and  others  the  superior  external  portion  of  the  knee 
joint. 

3.  The  Middle  Articular  Artery  {Art.  Articularis  Me- 
dia) is  smaller  than  either  of  the  above,  and  sometimes 
comes  from  one  of  them,  but  generally  from  the  popliteal, 
on  a line  with  the  articulation  of  the  knee.  It  is  distributed 
to  the  posterior  part  of  the  capsular  ligament,  to  the  crucial 
ligaments,  and  to  the  corresponding  adipose  matter. 

4.  The  Inferior  Internal  Articular  Artery  {Art.  Articu- 
laris Inferior  Interna)  arises  on  a line  with  the  inferior 
part  of  the  internal  condyle,  sometimes  lower  down.  Its 
origin  is  very  much  concealed  by  the  internal  head  of  the 
gastrocnemius;  it  passes  beneath  the  latter,  and  then  be- 
tween the  internal  lateral  ligament  of  the  knee  and  the  head 
of  the  tibia,  consequently  is  covered  by  the  internal  ham-  m 
string  muscles.  It  afterwards  ascends  towards  the  patella, 
and  is  distributed,  in  numerous  branches  to  the  inferior  in- 


I’lBIAI,  ARTERY. 


241 


ternal  part  of  the  knee  joint,  and  to  the  adjacent  portion  of 
the  tibia. 

5.  The  Inferior  External  A.rticular  Artery  {Jirt.  Jlrticu- 
laris  Inferior  Externa)  arises  near  the  last,  below  the  ex- 
ternal condyle,  being  concealed  by  the  belly  of  the  plantaris. 
It  passes  horizontally,  or  nearly  so,  between  the  popliteus 
and  the  outer  head  of  the  gastrocnemius,  and  afterwards 
beneath  the  tendon  of  the  biceps  and  the  external  lateral 
ligament  of  the  joint,  around  the  external  face  of  the  head 
of  the  tibia.  It  gives  small  branches  to  these  several  parts, 
and  is  then  distributed,  by  two  orders  of  ramifications,  to 
the  superficial  and  to  the  more  deeply  seated  parts  at  the 
external  inferior  portion  of  the  knee  joint. 

These  several  articular  arteries  anastomose  freely  with 
each  other,  and  are  minutely  ramified  on  the  knee  joint  and 
the  contiguous  structure.  They  also  anastomose  with  the 
long  descending  branch  of  the  external  circumflex  of  the 
thigh,  with  the  anastomotica  of  tlie  femoral  and  with  the 
tibial  recurrent. 

6.  The  Gastrocnemial  Arteries  {Jirteriae  Gerfiellse)  are 
two  in  number,  one  for  each  head  of  the  gastrocnemius.  They 
arise  commonly  between  the  superior  and  the  inferior  arti- 
cular arteries,  and  are  about  the  same  size.  They  penetrate- 
into  the  muscle  and  supply  it  with  blood,  terminating  their 
course  near  the  lower  part  of  its  bellies. 

Moi'eover  some  small  branches,  which  go  to  the  contigu- 
ous muscles,  are  frequently  observed  here;  also,  the  nutri- 
tious artery  of  the  tibia.  But  their  number  and  condition 
are  very  inconstant.  Near  the  head  of  the  fibula,  branches 
go  from  the  popliteal  artery  to  the  upper  end  of  the  soleus 
muscle. 

Generally  on  a level  with  the  aperture  in  the  upper  part  of 
the  interosseous  ligament,  but  sometimes  an  inch  or  two 
higher  up,  the  popliteal  artery  terminates  by  dividing  into 
two  large  trunks,  the  Anterior  and  the  Posterior  Tibial. 
VoL.  II.— 31 


242 


CIRCULATORY  SYSTEM. 


The  Anterior  Tibial  Artery  Tibialis  Jlnterior) 

passes  forwards  through  the  foramen  of  the  interosseous  liga- 
ment, just  below  the  head  of  the  fibula,  and  runs  down  the  front 
of  the  leg  and  foot,  as  far  as  the.  base  of  the  metatarsal  bone  of 
the  great  toe.  In  this  course  its  relative  situation  is  as  fol- 
lows. It  rests  upon  the  front  of  the  interosseous  ligament  of 
the  leg,  on  a line  drawn  from  the  middle  anterior  part  of  the 
head  of  the  fibula  to  the  middle  of  the  ankle  joint.  Superiorly 
it  is  bounded  on  the  tibial  side  by  the  tibialis  anticus  muscle, 
and  on  tlie  other  by  the  extensor  longus  digitorum;  lower 
down  on  the  leg,  the  place  of  the  latter  is  supplied  by  the 
extensor  pollicis  pedis.  Somewhat  above  the  ankle  joint  the 
artery,  leaving  the  interosseous  ligament,  rests  upon  the  front 
of  the  tibia,  and  then  gets  to  the  top  of  the  foot,  between  the 
joint  and  the  annular  ligament.  Under  the  ligament  it  is 
crossed  by  the  tendon  of  the  extensor  pollicis,  which  gets  to 
its  inner  side,  and  afterwards  continues  so.  The  anterior 
tibial  nerve  adheres  to  it,  in  its  whole  length. 

The  following  branches  come  from  the  anterior  tibial 
arteiy: 

1.  The  Recurrent  Tibial  {Jirt.  Tibialis  Recurrens)  as- 
cends through  the  upper  extremity  of  the  tibialis  anticus  mus- 
cle, having  come  off  from  the  anterior  tibial  immediately  upon 
the  latter  getting  to  the  front  of  the  leg.  Several  small 
ramifications  pass  from  it  to  the  heads  of  the  contiguous  mus- 
cles on  the  , tibia,  and  to  the  lower  part  of  the  knee  joint, 
where  it  anastomoses  with  the  lower  articular  arteries  of  the 
knee. 

2.  Sevei-al  Small  arterial  twigs  are  afterw’ards  sent  to  the 
muscles  and  to  the  periosteum  of  the  leg,  as  the  anterior 
tibial  descends,  but  they  are  two  inconstant  in  size  and  po- 
sition to  require  description. 

3.  The  Internal  Malleolar  Artery  {Jlrt.  Malleolaris  In- 
terna) arises  from  the  anterior  tibial  an  inch  or  two  above 
the  ankle  joint.  It  descends  inwardly  between  the  tibia  and 


TIBIAL  ARTERT. 


243 


the  tendon  of  the  tibialis  anticus,  and  having  gained  the  in- 
ternal malleolus,  is  distributed  by  branches  upon  it  and  upon 
the  adjacent  portion  of  the  articulation. 

4.  The  External  Malleolar  Artery  {Art.  Malleolar-is  Ex- 
terna) consists  most  commonly  in  two  arterial  twigs  of 
small  size,  but  frequently  in  one  only.  It  arises  in  front  of 
the  ankle  joint,  and  going  outwardly  between  it  and  the  ten- 
dons of  the  extensor  digitorum  longus,  is  spent  upon  the  ex- 
ternal face  of  the  articulation,  where  it  inosculates  with  the 
peroneal  artery. 

This  artery  is  sometimes  of  considerable  size,  in  which 
case  it  also  supplies  the  outer  part  of  the  tarsus,  and  is  a 
substitute  for  the  next. 

5.  The  Tarsal  Artery  {Arteria  Tarsea)  arises  from  the 
anterior  tibial,  somewhat  below  the  ankle  joint  near  the  sca- 
phoides,  and,  going  outwardly  beneath  the  extensor  brevis 
digitorum  muscle,  it  is  distributed  in  branches  near  the  ex- 
ternal ankle,  and  upon  the  outer  upper  surface  of  the  tarsus. 
It  anastomoses  with  the  external  malleolar,  with  the  exter- 
nal plantar,  and  with  the  metatarsal  artery. 

Some  small  branches  also  pass  from  the  anterior  tibial  at 
this  point  to  the  upper  internal  face  of  the  tarsus. 

6.  The  Metatarsal  Artery  {Art.  Metatarsea)  arises  just 
below  the  last.  It  is  directed  forwards  and  outwards  be- 
neath the  extensor  brevis  muscle,  and  forms  a sort  of  arch 
at  the  roots  of  the  metatarsal  bones.  It  furnishes  several 
ramifications  to  the  upper  surface  of  the  tarsus  and  the  con- 
tiguous parts;  amongst  them  is  an  interosseal  artery  for  each 
of  the  three  outer  interosseal  spaces.  These  arteries  com- 
municate, by  small  anastomoses,  with  the  arteries  of  the  sole 
of  the  foot,  both  at  the  bases  and  at  the  ends  of  the  metatar- 
sal bones,  and  terminate  in  front  by  supplying  the  backs  of 
the  small  toes. 

This  artery  is  sometimes  a branch  of  the  tarsal. 


CIRCULATORY  SYSTEM. 


•!-14 

7.  The  Dorsal  Artery  of  the  Great  Toe  {Art.  Dorsalis 
Hallucis)  arises  from  the  anterior  tibial  at  the  root  of  the 
first  metatarsal  bone.  It  runs  along  the  superior  face  of  the 
hrst  metatarsal  interval,  and,  having  reached  the  anterior 
end  of  it,  divides  into  two  branches,  one  of  which  goes  to  the 
back  of  the  great  toe  and  the  other  to  the  tibial  margin  of  the 
next  toe. 

The  Anterior  Tibial,  in  its  course  from  the  ankle  joint  to 
the  base  of  the  first  metatarsal  bone,  is  sometimes  called  pe- 
dal {Arteria  Pedicea;)  at  the  posterior  end  of  the  first  me- 
tatarsal interval,  being  still  of  considerable  size,  it  sinks 
down  to  the  sole  of  the  foot,  and  joins  itself  to  the  external 
plantar  artery  at  this  point. 

It  frequently  happens  that  the  anterior  tibial  being  small 
in  its  course  down  the  leg,  is  joined  by  the  continued  trunk 
of  the  peroneal,  which  perforates  the  interosseous  ligament 
somewhat  above  the  ankle  joint.  Afterwards  the  trunk 
formed  by  this  union,  being  of  considerable  size,  follows 
the  course  and  has  the  distribution  mentioned. 

The  Posterior  Tibial  Artery  {Arteria  Tibialis  Posiica) 
sometimes  called,  at  its  commencement  till  it  gives  olf 
the  peroneal,  tibio-peronealj  extends  from  the  head  of  the 
tibia  to  the  sinuosity  of  the  os  calcis,  in  a line  from  the 
middle  of  the  ham  to  the  internal  ankle.  It  is  at  the  tibial 
side  of  the  back  of  the  leg,  on  the  posterior  face  of  the  flexor 
longus  digitorum  muscle,  and  covered  by  the  fascia  of 
the  latter.  In  the  two  superior  thirds  of  its  course,  it  is 
concealed  behind  by  the  gastrocnemius  and  the  solseus  mus- 
cles; in  the  inferior  third,  it  is  at  the  internal  margin  of  the 
tendo  achillis.  At  the  ankle  joint,  before  it  passes  into  the 
sinuosity  of  the  os  calcis,  it  is  between  the  tendon  of  the 
tibialis  posticus  and  that  of  the  flexor  longus  pollicis  pedis, 
being  covered  by  the  laciniated  ligament.  It  is  accompanied, 
at  its  external  margin,  by  the  posterior  tibial  nerve. 

The  posterior  tibial  artery  is  distributed  after  the  follow- 
ing manner; 


245 


TIBIA*L  ASTBRT. 

1.  The  Peroneal  Artery  {Jirteria  Pero7iea)  is  fts  first 
branch  of  any  importance,  and  is  but  little  smaller  than  the 
continued  trunk.  It  arises  an  inch  or  two  below  the  ante- 
rior tibial,  and  extends,  on  the  posterior  face  of  the  leg,  to 
the  external  ankle.  It  is  in  some  measure  concealed  by  the 
posterior  side  of  the  fibula,  being  placed  there  between  the 
origin  of  the  flexor  longus  pollicis  muscle  and  the  external 
edge  of  the  tibialis  posticus.  It  is  consequently  covered  be- 
hind by  the  flexor  longus  pollicis,  by  the  soleus,  and  by  the 
gastrocnemius;  it  is  therefore  deep  and  of  extremely  difficult 
access  in  the  living  body. 

In  this  course  it  sends  small  branches  to  the  gastrocne- 
mius, to  the  soleus,  and  to  the  other  contiguous  muscles  on 
the  back  of  the  leg.  After  having  descended  two-thirds  of 
the  length  of  the  fibula,  it  divides  into  an  anterior  and  a 
posterior  branch.  The  former  traverses  the  interosseous  li- 
gament, and,  descending  in  front  of  it  covered  by  the  mus- 
cles which  arise  from  the  lower  part  of  the  fibula,  is  distri- 
buted upon  the  upper  external  part  of  the  foot  near  the 
ankle  joint.  The  posterior  branch  continues  in  the  primitive 
course  of  the  peroneal  artery  at  the  internal  posterior  mar- 
gin of  the  fibula,  and,  descending  behind  the  tibio-peroneal 
articulation,  reaches  the  external  face  of  the  os  calcis;  it 
detaches  several  small  ramifications  to  the  contiguous  mus- 
cles; and,  upon  the  os  calcis,  is  divided  into  twigs  which 
supply  the  adjacent  parts  and  the  integuments  below  the 
external  ankle. 

2.  In  the  descent  of  the  posterior  tibial  artery  to  the  hol- 
low of  the  os  calcis,  it  detaches  several  small  muscular 
branches,  principally  to  the  tibialis  posticus  and  to  the  flex- 
ors of  the  toes.  One  twig,  which  is  the  nutritious  artery  of 
the  tibia,  comes  from  its  upper  part  when  not  furnished 
from  the  popliteal  artery,  and  enters  the  foramen  on  the 
posterior  surface  of  the  bone. 

While  the  posterior  tibial  is  in  the  hollow  of  the  os  calcis, 
between  it  and  the  abductor  muscle  of  the  great  toe,  it  fur- 
nishes some  small  twigs  to  the  contiguous  muscles,  and  to 


S46 


CIRCTTLATORV  SYSTEM. 


the  integuments  of  the  sole  of  the  foot;  it  then  divides  into 
two  branches,  the  Internal  and  the  External  Plantar  Artery. 

The  Internal  Plantar  Artery  {Jift.  Plantaris  Interna)  is 
much  smaller  than  the  other.  It  advances  between  the  ab- 
ductor pollicis  pedis  and  the  internal  inferior  margin  of  the 
sole  of  the  foot,  and  terminates  at  the  anterior  end  of  the 
first  metatarsal  bone,  by  joining  the  internal  digital  artery 
of  the  great  toe.  In  this  course,  it  sends,  continually,  small 
ramifications  to  the  muscles  of  the  great  toe  and  to  the  flexor 
brevis  digitorum  pedis.  One  of  the  largest  of  these  ramifica- 
tions comes  off  near  the  os  scaphoides,  and  cruises  along 
the  internal  margin  of  the  abductor  pollicis  to  its  anterior 
end;  another  becomes  superficial  on  the  sole  of  the  foot,  be- 
tween the  abductor  pollicis  and  the  flexor  brevis,  and  goes 
forward  as  far  as  the  other. 

The  External  Plantar  Artery  {Art.  Plantaris  Externa) 
is  the  continuation  of  the  posterior  tibial,  and  diverges  from 
the  internal  plantar  towards  the  outer  margin  of  the  sole  of 
the  foot,  between  the  flexor  brevis  digitorum  pedis  and  the 
flexor  accessorius.  Having  reached  the  internal  margin  of 
the  abductor  minimi  digiti,  it  advances  along  the  latter  to 
the  base  of  the  metatarsal  bone  of  the  fourth  toe;  it  then 
makes  a curvature  forwards  and  inwards  across  the  meta- 
tarsal bones,  between  the  tendons  of  the  flexor  longus  and 
the  interosseous  muscles,  to  the  first  metatarsal  interval, 
where  it  is  joined  by  the  anterior  tibial  artery  from  above. 
This  curvature  is  the  Arcus  Plantaris,  of  which  the  conca- 
vity is  behind  and  inwards. 

The  external  plantar  artery  is  distributed  as  follows: 

Shortly  after  its  origin,  it  detaches  a branch  which  goes 
backwards  and  outwards,  and  which,  keeping  close  to  the 
os  calcis  in  front  of  its  tuberosity,  is  distributed  to  the 
heads  of  the  muscles  arising  from  it,  and  to  the  outer  sur- 
face of  the  heel;  it  also  sends  an  arteriole  along  the  external 
edge  of  the  abductor  minimi  digiti. 

At  the  base  of  the  fourth  metatarsal  bone,  arises  a branch 


TIBIAL  ARTEKT. 


247 


called  the  External  Digital  Artery  of  the  Little  Toe.  It 
goes  at  first  deeply  along  the  internal  margin  of  the  mus- 
cles situated  on  the  fifth  metataisal  bone,  and  afterwards,  at 
the  head  of  the  latter,  it  gets  between  them  and  the  bone, 
and  is  distributed  along  the  external  margin  of  the  little  toe. 

The  four  Digital  Arteries  of  the  foot  arise  next  succes- 
sively from  the  arcus  plantaris,  at  or  near  the  metatarsal 
intervals.  They  run  along  the  inferior  surface  of  the  inter- 
osseous muscles,  getting  to  the  bases  of  the  first  phalanges 
above  the  transversalis  pedis.  Each  artery  there,  bifurcates 
so  as  to  supply  the  opposed  surfaces  of  the  adjacent  toes. 

The  digital  artery  of  the  first  metatarsal  interval  which 
comes  from  the  internal  extremity  of  the  arcus  plantaris, 
where  the  anterior  tibial  artery  joins  the  latter;  goes  for- 
wards concealed  by  the  flexor  brevis  of  the  great  toe;  just 
behind  the  sesamoid  bones,  it  sends  a branch  which  sup- 
plies the  internal  side  of  the  great  toe,  being  its  internal 
digital  artery,  and  anastomoses  with  the  internal  plantar 
artery.  What  remains  of  it,  is  still  a trunk  of  considerable 
magnitude,  which  advancing  to  the  space  between  the  first 
phalanges  of  the  great  toe  and  of  the  toe  next  to  it,  there 
bifurcates,  as  mentioned,  so  as  to  supply  the  opposed  sides 
of  these  two  toes. 

The  Perforating  Arteries,  as  they  are  called,  are  of  two 
kinds,  the  anterior  and  the  posterior.  The  former  arise 
from  the  convexity  of  the  plantar  arch,  and  being  destined 
principally  to  the  interosseous  muscles,  anastomose  at  the 
anterior  end  of  the  latter  with  the  branches  from  the  meta- 
tarsal artery,  which  supply  their  superior  surface.  The  pos- 
terior perforating  arteries  come  also  from  the  plantar  arch, 
and  penetrating  the  posterior  end  of  the  interosseous  spaces, 
anastomose  also  with  the  metatarsal  arteries  on  the  dorsum 
of  the  foot. 

The  preceding  trunks  of  the  internal  and  of  the  external 
plantar  arteries  are  the  pi'incipal  ones  which  are  found  in 
the  bottom  of  the  foot,  but  from  them  there  arise  an  im- 


1 

248  CIRCULATOEY  SYSTEM. 

mense  number  of  arterioles;  which,  descending  vertically 
between  the  interstices  of  the  muscles  and  of  the  aponeu' 
rosis  plantaris,  supply  the  adipose  matter  and  the  skin  of  the 
sole  of  the  foot,  so  as  to  render  them  extremely  vascular. 


CHAPTER  III. 

OF  THE  VEINS. 

The  veins  of  the  body,  assembling  from  different  points, 
unite  successively  into  the  ascending  and  into  the  descending 
vena  cava,  which  discharge  their  blood  into  the  right  auricle 
of  the  heart.  The  veins  of  the  head,  of  the  upper  extremi- 
ties, and  of  the  thorax,  run  into  the  descending  cava,  while 
the  veins  of  the  abdomen  and  of  the  lower  extremities  con- 
cur to  form  the  ascending  cava. 


SECT.  I. — OP  THE  VEINS  OP  THE  HEAD  AND  NECK. 

Many  of  these  veins  are  described  elsewhere  with  the  en- 
cephalon and  with  the  eye,  to  which  account  the  reader  is 
referred.  The  others  are  more  superficial,  and  arise  as  fol- 
lows: 

The  Facial  Vein  {Vena  Facialis)  observes  the  course  of 
the  facial  artery,  being  placed  behind  the  latter.  It  arises 
upon  the  forehead  by  a considerable  number  of  roots  which 
unite  into  a single  trunk  called  the  frontal  vein.  This  vein 
descends  from  the  forehead,  over  the  root  of  the  nose  along 
the  internal  canthus  of  the  orbit.  It  there  receives  re-en- 
forcements from  the  eyelids,  and  anastomoses  with  the  oph- 
thalmic veins;  descending  afterwards,  in  the  same  way  with 
the  facial  artery,  and  taking  the  name  of  facial  vein,  it  re- 
ceives successively  the  veins  from  the  nose,  from  the  outer 


-VEINS  OP  THE  HEAD  AND  NECK. 


249 


side  of  the  orbicularis  palpebrarum,  from  the  upper  and 
lower  lips,  and  from  the  muscles  and  the  integuments  of  the 
face.  It  descends  to  the  neck  at  the  anterior  margin  of  the 
masseter  muscle,  and  is  then  augmented  by  the  ranine,  the 
submental,  and  the  inferior  palatine  veins,  and  immediately 
afterwards  goes  into  the  internal  or  the  external  jugular 
vein. 

The  Ranine  Vein  ( Vena  Ranina)  arises  at  the  point  of 
the  tongue,  and  then  goes  along  its  under  surface,  where  it 
can  be  readily  seen  by  turning  up  the  end  of  the  tongue.  It 
joins  the  facial  near  the  posterior  margin  of  the  mylo-hyoi- 
deus  muscle. 

The  Submental  Vein  {Vena  Submentalis)  arises  by  ra- 
muscles  from  the  sublingual  and  submaxillary  glands,  and 
from  the  contiguous  muscles.  It  joins  the  facial  vein  a lit- 
tle below  the  last:  sometimes  it  runs  into  the  superior  thy- 
roidal vein. 

The  Inferior  Palatine  Vein  {Vena  Palatina  Inferior) 
arises  principally  from  the  soft  palate  and  from  the  tonsil 
gland,  but  receives  a few  twigs  from  the  contiguous  parts. 
It  corresponds  with  the  inferior  palatine  artery  and  descends 
the  pharynx  along  side  of  it,  and  terminates  in  the  trunk  of 
the  facial  near  the  last. 

The  Lingual  Vein  ( Vena  Lingualis)  has  its  origin  from 
a plexus  of  veins  situated  on  the  root  of  the  tongue  under  its 
lining  membrane,  between  the  epiglottis  and  the  foramen 
caecum:  branches  are  also  sent  to  it  from  the  muscular 
structure  of  the  tongue,  from  the  sublingual  gland,  and  from 
the  adjacent  muscles,  and  it  anastomoses  with  the  yena  ra- 
nina. It  goes  backwards  between  the  hyo-glossus  and  the 
mylo-hyoideus  muscles  along  the  superior  margin  of  the  os 
hyoides,  and  then  discharges  into  the  internal  jugular  vein 
near  the  facial. 

The  Pharyngeal  Vein  ( Vena  Pharyngea)  arises  from  a 
plexus  of  veins  belonging  to  the  pharynx,  and  discharges 
either  into  the  lingual  or  into  the  internal  jugular  near  it. 

The  Superior  Thyroid  Vein  ( Vena  Thyroidea  Superior) 
corresponds  with  the  distribution  of  the  superior  thyroid  ar- 

Voi,.  II. — 33 


•■250 


CIRCULATORY  SYSTEM. 


tery  in  the  origin  of  its  primitive  roots.  Having  collected 
the  latter  into  one  or  more  trunks,  it  passes  upw^ards  and 
backwards  beneath  the  sterno-hyoid  and  thyroid  muscles, 
and  discharges  itself  into  the  upper  part  of  the  internal 
jugular,  or  into  one  of  the  large  branches  of  the  external 
jugular. 

The  Occipital  Vein  [Vena  Occipitalis)  arises  from  the 
branches  of  the  occipital  artery,  and  following  the  course  of 
the  latter,  beneath  the  muscles  connected  with  the  mastoid 
process  of  the  temporal  bone;  it  is  discharged  into  the  upper 
part  of  the  internal  jugular  or  of  the  external,  more  rarely 
into  the  latter. 

The  Diploic  Veins  ( Vense  Diploicse)  have  been  described 
in  the  account  of  the  bones  of  the  cranium  as  situated  be- 
tween the  two  tables  in  the  diploic  structure,  and  commence 
by  very  fine  capillary  tubes  from  its  lining  membrane. 
The  one  in  the  frontal  bone  discharges  itself  into  the  fron- 
tal vein,  that  in  the  occipital  bone  into  the  occipital  vein, 
and  the  two  in  the  parietal  bone  into  the  deep  temporal 
veins.  They  do  not  open  each  by  one  orifice,  but  by  se- 
veral, which  makes  their  termination  not  very  distinct  or 
abrupt;  besides  which,  they  communicate  freely  by  a crowd 
of  ramuscles,  with  the  veins  of  the  scalp  on  the  outside,  and 
with  those  of  the  dura  mater  internally. 

The  Superficial  Temporal  Vein  [Vena  Temporalis  Su- 
perjicialis)  corresponds  with  the  temporal  artery,  and  takes 
its  rise  from  the  terminating  ramifications  of  the  latter.  It 
is  immediately  below  the  skin.  Its  branches  communicate 
freely  with  each  other,  and  with  the  branches  of  the  frontal 
and  of  the  occipital  veins:  at  the  zygoma  it  receives  the 
trunk  of  the  Middle  Temporal  Vein,  which  collecting  the 
blood  from  the  temporal  muscle  and  other  parts  within  the 
zygoma,  perforates  the  temporal  fascia  to  discharge  itself 
into  the  superficial  temporal  vein. 

The  Temporal  Vein,  ( Vena  Temporalis^\v\i\eh  is  formed 
by  the  junction  of  the  Middle  and  the  Superficial  Temporal, 
descends  over  the  root  of  the  zygoma,  in  company  with 
the  artery,  and  penetrates  like  the  latter  through  the  sub- 
stance of  the  parotid  gland.  It  is  joined  near  the  neck  of 


VEINS  OF  THE  HEAD  AND  NECK. 


251 


the  lower  faw  by  the  internal  maxillary  vein.  It  is  also 
joined,  in  its  descent  through  the  parotid  gland,  by  the  an- 
terior auricular  veins,  by  the  parotid  veins,  and  by  the 
transverse  facial,  all  of  which  correspond  with  the  arteries 
of  the  same  name.  The  temporal  vein,  on  issuing  from  the 
parotid  gland,  immediately  afterwards  becomes  the  Exter- 
nal Jugular, 

The  Internal  Maxillary  Vein  {Vena  Maxillaris  Inter- 
na) is  derived  from  the  terminating  ramifications  of  all  the 
arteries  into  which  the  internal  maxillary  is  split;  it  is  there- 
fore composed  of  the  spheno-palatine  vein,  which  brings  the 
blood  from  the  nose,  of  the  infra-orbital,  of  the  pterygoids, 
inferior  maxillary,  deep-seated  temporal,  and  so  forth,  with 
the  exception  of  the  vein  which  might  belong  to  the  mid- 
dle artery  of  the  dura  mater,  but  which  does  not  exist  ac- 
cording to  Portal  and  to  Hippolytus  Cloquet,  But,  by  the 
aid  of  the  spheno-palatine  vein,  the  internal  maxillary  com- 
municates with  the  sinuses  in  the  bottom  of  the  cranium, 
by  branches  called  the  Emissary  Veins  of  Santorini,*  which 
pass  through  the  foramen  ovale,  rotundum,  and  spinale.  It 
also  communicates  with  the  plexus  of  veins  on  the  side  of 
the  Pharynx. 

The  External  Jugular  Vein  ( Vena  Jugularis  Externa) 
is  the  continuation  of  the  temporal.  It  descends  on  the  neck 
almost  vertically,  between  the  platysma  myoides  and  the 
sterno-mastoideus,  in  the  direction  of  the  fibres  of  the  first, 
and  crossing  those  of  the  latter  obliquely.  Just  behind  the 
clavicle,  at  the  external  margin  of  tiie  sterno-mastoideus,  it 
opens  into  the  subclavian  vein,  in  front  of  the  scalenus  an- 
ticus  muscle.  Sometimes,  instead  of  one  trunk  only,  there 
are  two  or  three,  which  unite  at  a variable  distance  above 
the  subclavian.  This  vein  varies  also  in  its  size,  and  in  the 
branches  from  which  it  is  made  up;  sometimes  it  receives 
the  facial  vein,  and  on  other  occasions  the  latter  runs  into 
the  internal  jugular.  The  temporal  vein  is  also  sometimes 
continued  in  part  or  wholly  into  the  internal  jugular.  The 

* Obs.  Anat.  chap,  iii.  p.  74. 


'^52 


CIRCULATORY  SYSTEM. 


condition  and  arrrangement  of  the  internal  and  external  ju- 
gulars are  indeed  so  inconstant,  in  regard  to  the  trunks  that 
compose  them,  that  it  is  scarcely  possible  to  give  more 
than  a very  general  description  of  them  with  tolerable  accu- 
racy. 

The  external  jugular,  in  going  down  the  neck,  anasto- 
moses more  or  less  with  the  internal  jugular,  either  directly 
or  by  its  branches:  one  of  these  anastomoses  is  found  near 
the  angle  of  the  lower  jaw,  about  the  trunk  of  the  facial 
vein,  and  is  so  large  as  to  explain  the  difference  of  opi- 
nion among  anatomists  in  regard  to  the  latter’s  termination. 
Sometimes  the  occipital  yein,  or  a large  trunk  from  it,  joins 
the  external  jugular  At  the  lower  part  of  the  neck,  the 
external  jugular  is  augmented  by  the  superficial  cervical 
veins.  Some  of  these  come  from  the  lower  part  of  the 
neck,  near  the  shoulder,  and  join  the  jugular  just  above  the 
clavicle;  others  are  placed  on  the  lower  front  part  of  the 
neck,  above  the  sternum,  and  there  form  with  each  other 
a remarkable  and  an  irregular  plexus,  consisting  in  nume- 
rous meshes.  It  frequently  happens  that  the  external  jugu- 
lars of  the  two  sides,  just  before  they  terminate,  anastomose 
with  each  other  by  a large  horizontal  trunk,  which  runs 
just  above  the  end  of  the  sternum,  in  front  of  the  sterno- 
mastoid,  sterno-hyoid,  and  the  thyroid  muscles;  this  trunk, 
on  other  occasions,  goes  more  deeply,  and  behind  these 
muscles,  from  one  subclavian  vein  to  another,  or  to  a jugu- 
lar; its  mode  of  attachment  is  indeed  much  varied:  when 
it  exists,  however,  it  frequently  receives  several  of  the  su- 
perficial veins  of  the  neck,  and  the  inferior  thyroidal. 

The  Internal  Jugular  Vein  (F'ena  Jugularis  Interna) 
extends  from  the  basis  of  the  cranium  to  the  internal  mar- 
gin of  the  first  rib,  at  the  insertion  of  the  scalenus  anticus 
muscle.  The  lateral  sinuses  of  the  dura  mater,  receiving 
ultimately  all  the  blood  of  the  brain,  of  the  eye,  and  a por- 
tion of  that  of  the  nose,  convey  it  from  the  cranium  through 
the  posterior  foramina  lacera,  where  they  are  joined  to  the 
upper  end  of  the  internal  jugular  veins,  the  lining  mem- 
brane of  each  sinus  being  continuous  with  that  of  its  respec- 


VEINS  OF  THE  HEAD  AND  NECK. 


253 


live  veins.  Each  vein  is  somewhat  enlarged  at  its  com- 
mencement, which  is  therefore  called  its  Gulph  or  Sinus; 
the  right  vein  is  frequently  larger  than  the  left.  The  in- 
ternal jugular  then  descends  in  front  of  the  transverse  pro- 
cesses of  the  vertebrae  of  the  neck,  on  the  outer  side  of  the 
internal  end  of  the  primitive  carotid  artery,  and  of  the 
pneumogastric  nerve.  It  is  concealed  above  by  the  styloid 
process  of  the  temporal  bone,  and  the  muscles  belonging  to 
it;  it  is  crossed  half  way  down  the  neck  by  the  omo-hyoi- 
deus  muscle;  and,  in  the  greater  part  of  its  course,  is  be- 
neath, and  nearly  parallel  with,  the  anterior  edge  of  the 
sterno-mastoideus.  Having  got  behind  the  sternal  end  of 
the  clavicle,  it  is  joined  at  the  internal  edge  of  the  scalenus 
anticus  by  the  subclavian  vein,  and  the  union  of  the  two 
forms  the  vena  innominata. 

The  internal  Jugular  receives  frequently  a large  anasto- 
motic branch  from  the  external  jugular,  at  the  under  margin 
of  the  parotid  gland,  between  the  digastric  muscle  and  the 
lower  jaw,  and  it  is  in  this  vicinage  that  it  is  generally  re- 
enforced by  the  Occipital;  the  Lingual;  the  Facial;  the  Pha- 
ryngeal; and  the  Superior  Thyroidal  veins,  that  have  been 
described. 

The  Vena  Innominata  or  Brachio  Cephalic  Vein,  is  the 
trunk  formed  on  either  side  by  the  junction  of  the  subcla- 
vian with  the  internal  jugular.  On  the  right  side  it  looks 
like  the  continuation  of  the  internal  jugular,  and  descends 
in  contact  with  the  right  pleura,  behind  the  right  side  of 
the  sternum,  for  the  distance  of  an  inch  or  thereabouts.  On 
the  left  side  it  crosses  behind  the  superior  end  of  the  ster- 
num, descending  obliquely  in  this  course,  from  left  to  right, 
until  it  joins  the  trunk  on  the  right  side.  It  lies  in  front 
of  the  great  vessels  proceeding  from  the  arch  of  the  aorta; 
and  is  much  longer  than  the  trunk  of  the  other  side. 

The  Vena  Cava  Superior  or  Descendens  arises  from  the 
junction  of  the  two  venae  innominatae.  It  begins  between 
the  cartilage  of  the  first  rib  on  the  right  side,  and  the  arch 


254 


CIRCULATORY  SYSTEM. 


of  the  aorta,  and  descends  to  the  superior  posterior  part  of 
the  right  auricle,  into  which  it  empties  itself.  Its  course  is 
not  entirely  vertical,  but  inclining  somewhat  to  the  leftside 
and  forward.  It  is  about  three  inches  long.  The  superior 
third  of  it  is  free,  is  in  contact  on  the  right  with  the  pleura, 
and  on  the  left  with  the  arteria  innominata;  the  remaining 
portion  of  it  is  invested  by  the  pericardium,  and  has  the 
aorta  on  its  left  anterior  face.* 

The  following  venous  trunks  discharge  into  the  venae  in- 
nominatae,  or  into  the  descending  cava.  The  inferior  Thy- 
roidal; the  Vertebral;  the  Superior;  Intercostal;  the  In- 
ternal Mammary;  the  Vena  Azygos;  and  some  others  of 
smaller  size. 

1.  The  Inferior  Thyroid  Vein  {Vena  Thyroidea  Infe- 
rior) arises  from  the  inferior  part  of  the  thyroid  gland,  by 
many  small  roots,  w'hich  anastomose  with  those  of  the  op- 
posite side.  It  descends  in  front  of  the  trachea,  involved 
in  the  loose  cellular  and  fatty  matter  lying  upon  it,  and 
empties  itself  into  the  left  brachio-cephalic  vein. 

There  is  occasionally  another  thyroid  vein,  called  the 
middle,  which  discharges  itself  into  the  lower  part  of  the 
internal  jugular. 

2.  The  Vertebral  Vein  {Vena  Vertebralis)  is  placed  in 
the  same  canal  with  the  vertebral  artery.  At  its  upper  ex- 
tremity it  anastomoses  with  the  occipital  sinus,  by  a branch 
lodged  in  the  posterior  condyloid  foramen.  In  its  descent 
of  the  canal  of  the  transverse  processes,  it  communicates  at 
each  intervertebral  foramen  with  the  vertebral  sinuses,  and 
also  receives  a branch  from  the  muscles  of  the  neck.  It 
issues  at  the  sixth  transverse  process,  and  going  on  the  right 
side  behind  the  subclavian  artery,  but  on  the  left  in  front 
of  it,  it  is  finally  emptied  into  the  commencement  of  the 
vena  innominata. 

* In  some  very  rare  cases  there  have  been  two  descending' vense  cavK, 
one  for  the  right  side  and  the  other  for  the  left.  J.  F.  Meckel. 


VEINS  OP  THE  HEAD  AND  NECK. 


255 


3.  The  Superior  Intercostal  Vein  ( Vena  Intercostalis 
Superior)  is  on  the  right  side  an  inconsiderable  trunk, 
sometimes  deficient,  which  commences  by  branches  belong- 
ing to  the  two  first  intercostal  spaces,  and  empties  into  the 
vena  innominata  just  below  the  vertebral.  On  the  left  side 
it  is  much  larger,  and  arises  from  the  six  or  eight  superior 
intercostal  spaces.  It  lies  on  the  left  side  of  the  bodies  of 
the  upper  dorsal  vertebrae,  and  at  each  intercostal  space,  as 
it  ascends,  receives  its  contribution  of  an  intercostal  vein, 
corresponding  with  the  intercostal  artery;  it  also  receives 
branches  from  the  oesophagus,  and  about  the  third  dorsal 
vertebra  the  left  bronchial  vein  is  discharged  into  it.  Is- 
suing from  the  thorax  above,  it  discharges  into  the  left  vena 
innominata  near  its  commencement. 

4.  The  Internal  Mammary  Vein  ( Vena  Mammaria  In- 
terna) arises  from  the  terminating  branches  of  the  internal 
mammary  artery,  and  in  its  situation  and  course  corres- 
ponds with  the  latter.  It  is  re-enforced  by  small  branches 
from  the  diaphragm,  the  pericardium,  and  the  thymus 
gland.  Each  internal  mammary  vein  discharges  itself  on 
its  respective  side  into  the  vena  innominata  near  the  supe- 
rior intercostal. 

5.  The  Vena  Azygos  is  placed  in  the  posterior  medias- 
tinum, on  the  right  anterior  margin  of  the  Dorsal  Verte- 
brae, and  discharges  itself  in  making  an  arch  forwards  over 
the  root  of  the  right  lung,  into  the  descending  cava,  just 
above  the  introduction  of  the  latter  into  the  pericardium. 
Its  orifice  there  is  supplied  with  a membranous  duplicature 
or  valve,  which  prevents  the  blood  once  discharged  from 
re-entering  it.  The  valve  is  sometimes  double,  and  also 
somewhat  removed  from  the  orifice.  It  was  the  observa- 
tion of  these  valves,  first  of  all,  which  called  the  attention 
of  Sylvius  and  of  Charles  Etienne  to  their  existence  in 
other  veins. 

This  vein  begins  in  the  abdomen,  either  by  an  anasto- 
mosis with  the  ascending  cava,  or  with  the  upper  lumbar 
vein;  it  then  ascends  into  the  thorax  through  the  aortic  ori- 


256 


CIRCULATORY  SYSTEM. 


fice  of  the  diaphragm,  and  continuing  to  mount  upwards 
beneath  the  pleura,  it  lies  on  the  right  side  of  the  thoracic 
duct  and  crosses  in  front  of  the  intercostal  arteries  of  the 
right  side.  In  this  course  it  receives  from  the  ten  inferior 
intercostal  spaces  of  the  right  side,  their  respective  inter- 
costal veins  corresponding  in  their  origin  and  course  with 
the  intercostal' arteries.  About  the  sixth  vertebra  of  the 
back  it  receives  a trunk  ( Vena  Hemiazygos)  which  is 
formed  from  the  four  or  six  lower  intercostal  veins  of  the 
left  side,  and  commences  in  the  abdomen,  also,  by  an  anas- 
tomosis with  the  left  emulgent  vein  or  the  left  superior 
lumbar,  and  gets  into  the  thorax  either  through  the  aortic 
orifice  of  the  diaphragm,  or  through  a special  opening  to 
the  left  of  it.  The  vena  azygos  also  receives  some  small 
ramifications  from  the  oesophagus,  and  near  the  fourth  dor- 
sal vertebra,  the  right  bronchial  vein  is  discharged  into  it. 
Other  small  ramifications  join  it  from  the  parietes  of  the 
descending  cava;  of  the  aorta;  and  of  the  right  pulmonary 
artery.  Branches  also  proceed  to  it,  or  to  the  intercostal 
veins,  from  the  interior  of  the  vertebral  canal  at  each  inter- 
vertebral foramen. 

This  vein  is  commonly  spoken  of  by  anatomists,  as  form- 
ing a great  anastomosis  between  the  ascending  and  the  de- 
scending cava.  The  tendency  to  establish  this  anastomosis 
is  strikingly  confirmed  by  a preparation  made  sixteen  or 
seventeen  years  ago  by  myself,  and  now  in  the  Wistar 
Museum  of  the  University,  where  the  ascending  cava,  in- 
stead of  emptying,  as  usual,  into  the  lower  part  of  the  right 
auricle,  ascended  on  the  right  side  of  the  dorsal  vertebrse, 
and  supplanting  in  situation  and  office  the  vena  azygos,  dis- 
charged itself  into  the  descending  cava,  in  a manner  cor- 
responding with  the  vena  azygos,  by  making  a curvature 
forwards  over  the  root  of  the  right  lung. 

6.  The  Sinuses  of  the  Vertebral  Column*  [Sinus  Colum- 
ns Vertebralis)  are  situated  in  the  vertebral  cavity  on  the 
posterior  face  of  the  bodies  of  the  vertebras,  and  in  front  of  the 


* G.  Breschet,  Essai  sur  les  Veines  du  rachis.  Paris,  1819. 


VEKTEBKAL  SINUSES. 


251 


dura  mater  of  the  spinal  marrow.  They  are  two  long  veins, 
one  at  each  margin  of  the  posterior  vertebral  ligament,  and 
extend  from  the  foramen  magnum  occipitis  to  the  inferior 
end  of  the  sacrum.  They  are  maintained  in  their  places 
by  a loose  cellular  tissue  between  the  bones  and  the  dura 
mater,  and  therefore,  unlike  the  sinuses  of  the  brain,  are  en- 
tirely independent  of  the  dura  mater. 

These  sinuses  are  small  where  they  begin  in  the  sacrum, 
and  are  there  merely  two  cylindrical  veins  surrounded  by 
the  loose  cellular  matter,  and  which  have  an  anastomosis 
between  them.  In  ascending  the  spine  they  enlarge,  but 
not  continually,  as  they  are  somewhat  smaller  in  the  cer- 
vical than  in  the  dorsal  vertebrae.  On  the  body  of  each 
vertebra  they  are  rather  larger  than  on  the  inter- vertebral 
substance,  this  gives  them  a knotted  appearance,  which  is 
especially  distinct  in  the  loins. 

At  the  middle  of  each  vertebra  they  are  joined  to  one 
another  by  transverse  branches,  w ich  pass  beneath  the 
posterior  vertebral  ligament,  and  receive  the  veins  belong- 
ing to  the  cancellous  structure  of  the  bone.  Externally 
they  communicate  with  the  vertebral  veins  in  the  trans- 
verse processes  of  the  neck,  with  the  intercostal,  and  with 
the  lumbar  veins,  as  an  opening  occurs  between  the  adja- 
cent vertebrae.  They  also  receive  many  delicate  veins  from 
the  dura  mater  of  the  spine.  These  two  trunks  terminate 
at  their  upper  end  by  an  anastomosis,  through  the  anterior 
condyloid  foramen,  with  the  internal  jugular,  they  also  ter- 
minate by  anastomosis  with  the  anterior  occipital  sinus  and 
with  the  vertebral  veins. 

From  the  arrangement  of  these  sinuses,  it  appears  that 
each  bone  of  the  spine  has  its  own  venous  system  or  circle; 
which  also  is  the  case  in  regard  to  the  corresponding  section 
of  medulla  spinalis  in  early  life,  when  it  occupies  the  whole 
length  of  the  spine.  Each  of  these  circles,  by  the  free- 
dom of  their  anastomoses,  therefore,  forms  a link  in  a long 
chain  of  venous  circles  belonging  to  the  structure  of  the 
spine. 

VoL.  II. —33 


25S 


CiRCULATOKY  SYSTEM. 


SECT.  II. — OP  THE  VEINS  OP  THE  UPPER  EXTREMITY. 

The  veins  of  the  upper  extremity  are  superficial  and 
deep-seated,  and  arise  from  the  distribution  of  the  axillary 
artery. 

The  Deep-Seated  Veins  are  found  in  company  with  each 
arterial  ramification,  there  being  two  veins  to  one  artery  ge- 
nerally. We  thus  have  them  observing  the  course  of  the 
arteries  of  the  hand,  of  the  fore-arm,  of  the  arm,  and  of  the 
shoulder.  At  the  bend  of  the  arm,  the  two  radial  and  the 
two  ulnar  veins  coalesce  into  the  two  brachial  veins,  which 
attend  the  brachial  artery,  one  on  each  of  its  sides,  and  at 
intervals  throw  anastomotic  branches  across  it.  Sometimes, 
but  one  of  these  trunks  exists,  with  the  exception  of  the 
lower  part  of  the  arm,  where  there  are  most  commonly 
two.  The  trunk  (or  trunks,  as  the  case  may  be)  is  joined 
by  the  basilic  vein,  at  a point  varying  from  the  middle  of 
the  arm  to  the  axilla.  These  vense  comites,  or  satellites, 
are  invariably  called  after  the  arteries  which  they  attend, 
and  having  no  difference  from  the  latter  in  relative  situa- 
tion, a further  description  of  them  may  be  dispensed  with. 

The  Superficial  Veins  lie  between  the  skin  and  the  bra- 
chial aponeurosis,  and  are  considerably  larger  than  the  pre- 
ceding. Their  earliest  roots  are  seen  on  the  backs  of  the 
fingers;  they  then  appear  on  the  back  of  the  hand,  on  the 
posterior  face  of  the  lower  end  of  each  interosseous  space. 
There  are  commonly  six  trunks  in  all;  the  one  on  the  ulnar 
side  of  the  hand,  and  the  three  next  to  it,  converge  towards 
the  middle  of  the  back  of  the  carpus  into  a single  trunk;  the 
two  others,  one  of  which  comes  from  the  thumb  and  the 
other  from  the  back  of  the  fore-finger,  converge  to  the  outer 
end  of  the  carpus,  and  there  form  a single  trunk  also.  Be- 
tween these  several  trunks  there  are  frequent  anastomoses, 
and  they  finally  assemble  into  two  principal  branches  called 
the  Cephalic  and  the  Basilic  Vein. 


VEINS  OE  THE  UPPER  EXTREMITV.  259 

The  Cephalic  Vein  ( P^ena  Cephalica,  Radialis  Cutanea) 
is  the  trunk  which  comes  from  the  thumb  and  from  the  fore- 
finger, and  has  at  first  the  name  of  Cephalica  Pollicis.  It 
ranges  along  the  anterior  and  radial  margin  of  the  fore-arm, 
and  receives,  continually,  an  augmentation  from  small  col- 
lateral branches  on  the  back  of  the  fore-arm.  Having 
reached  the  bend  of  the  arm,  it  then  ascends  along  the  ex- 
ternal margin  of  the  biceps  flexor  cubiti  till  it  reaches  the 
lower  margin  of  the  pectoralis  major  muscle;  it  then  rises 
superficially  along  the  interstice  between  this  muscle  and 
the  deltoides,  to  within  eight  or  ten  lines  of  the  clavicle, 
where  it  dips  down  to  join  the  axillary  vein.  Along  the 
arm,  it  receives  some  small  secondary  cutaneous  branches. 

The  Basilic  Vein  ( Vena  Basilica,  Cubitalis  Cutanea)  is 
larger  than  the  cephalic,  and  begins  by  the  trunk  which 
comes  from  the  ulnar  side  of  the  back  of  the  hand,  and  is 
first  called  the  Vena  Salvatella.  On  the  fore-arm,  the  basilic 
frequently  consists  in  two  long  trunks,  the  anterior  and  the 
posterior:  in  this  case,  the  posterior  is  the  principal  one, 
and  runs  along  the  internal  posterior  edge  of  the  ulna  until 
it  comes  to  the  bend  of  the  arm;  it  then  mounts  over  the 
latter,  rising  obliquely  in  front  of  the  internal  condyle. 
The  anterior  branch  begins  near  the  palm  of  the  hand,  runs 
up  in  front  of  the  ulnar  side  of  the  fore-arm,  and  discharges 
itself  into  the  median  basilic  vein,  over  the  brachial  artery 
in  front  of  the  bend  of  the  arm.  These  two  trunks,  or  one 
as  the  case  may  be,  receive  the  cutaneous  veins  belonging 
to  the  ulnar  side  of  the  fore-arm. 

Above  the  elbow  joint,  the  basilic  gets  below  the  fascia 
of  the  arm  at  the  inner  edge  of  the  biceps,  and  about  the 
middle  of  the  arm  becomes,  by  its  junction  with  the  venae 
satellites,  the  Brachial  Vein;  but  sometimes,  as  mentioned, 
this  junction  occurs  much  higher  up. 

The  Median  Vein  ( Vena  Mediana)  arises,  by  branches, 
from  the  wrist,  from  the  palm  of  the  hand,  and  from  the 
middle  of  the  front  of  the  fore-arm.  It  forms  a trunk  which 


CIRCULATOKT  SVSTEM. 


2(i0 

ascends  in  front  of  the  radial  half  of  the  fore-armj  and 
which,  a few  inches  below  the  bend  of  the  arm,  divides 
into  two.  One  branch  runs  outwardly,  in  ascending,  for  an 
inch  or  two,  and  joins,  at  the  outer  side  of  the  bend  of  the 
arm,  the  cephalic  vein;  it  is  called,  therefore,  the  Median 
Cephalic.  The  other  branch  continues  to  ascend,  and  cross- 
ing obliquely  the  direction  of  the  brachial  artery,  it  re- 
ceives, near  the  latter,  the  anterior  trunk  of  the  basilic  vein, 
and  somewhat  above  the  bend  of  the  arm,  runs  into  the 
proper  basilic  vein;  it  is  called  the  Median  Basilic. 

There  is  frequently  a departure  from  the  preceding  ar- 
rangement of  the  median  vein;  the  most  common  is  where 
a trunk  begins  from  the  cephalic,  below  the  bend  of  the 
arm,  and  runs  up  obliquely  in  front  of  the  latter  to  join  the 
main  trunk  of  the  basilic  above  the  elbow  joint.  This  ob- 
lique trunk  stands  in  the  place  of  median  cephalic  and  me- 
dian basilic,  and  receives  successively  the  median,  the  an- 
terior, and  the  posterior  basilic.  It  is  frequently  the  median 
itself,  and  has  a short  anastomosis,  in  such  case,  with  the 
cephalic  vein. 

The  Superficial  Veins  anastomose  frequently  with  each 
other,  so  that,  when  they  are  all  fully  injected,  a plexus  of 
veins  is  found  immediately  beneath  the  skin  of  the  upper 
extremity  from  one  end  to  the  other.  The  Vense  Satellites 
also  anastomose  frequently  by  branches  which  cross  the  ar- 
tery to  which  they  belong.  At  the  bend  of  the  arm,  at  the 
wrist,  and  in  different  places  there  are  also  anastomoses  be- 
tween the  deep-seated  and  the  superficial  veins. 

The  Axillary  Vein  {Vena  ^obillaris)  results  from  the 
union  of  the  basilic  with  the  brachial  vein.  It  is  below  and 
in  front  of  the  axillary  artery,  being  included  in  the  same 
sheath  with  it,  and  also  involved  with  the  axillary  plexus  of 
nerves.  It  retains  its  name  from  the  lower  margin  of  the 
arm-pit  to  the  under  surface  of  the  clavicle,  where  like  the 
artery,  it  is  then  called  subclavian.  In  this  course  it  is 
joined  near  the  points  where  the  corresponding  arteries  are 


VEINS  OP  THE  LOWER  EXTEEMITV. 


2G1 


given  off,  by  the  Anterior  and  the  Posterior  Circumflex 
Veins;  by  the  Scapular;  and  by  the  External  Thoracic. 

The  Subclavian  Vein  ( Vena  Subclavia)  extends  from  the 
termination  of  the  axillary  to  the  vena  innominata,  where 
the  latter  is  constituted  by  the  junction  of  the  internal  jugu- 
lar with  the  subclavian.  In  its  course  it  goes  under  the 
subclavius  muscle,  and  is  in  front  of  the  subclavian  artery 
from  the  beginning,  but  near  it;  afterwards  it  is  separated 
from  the  artery  by  the  latter  going  between  the  anterior 
and  the  middle  scalenus  muscle,  whereas  the  vein  runs  over 
the  anterior  end  of  the  first  rib,  in  front  of  the  insertion  of 
the  scalenus  anticus. 

The  Subclavian  Vein  is  joined  by  some  branches  coming 
from  the  shoulder  and  from  the  lower  part  of  the  neck,  and, 
at  the  outer  margin  of  the  origin  of  the  sterno-mastoid  mus- 
cle: it  is  augmented  by  the  addition  to  it  of  the  external 
jugular.  It  terminates  at  the  internal  margin  of  the  scale- 
nus anticus,  as  mentioned  in  the  vena  innominata. 

SECT.  III. VEINS  op  THE  LOWER  EXTREMITY. 

The  veins  of  the  lower  extremity,  like  those  of  the  upper, 
are  deep-seated  and  superficial.  The  former  follow  the 
course  of  the  arteries,  and  are  the  venae  satellites;  there  be- 
ing, for  the  most  part,  two  veins  for  every  artery  as  far  up 
as  the  ham,  and  also  as  regards  the  muscular  branches  of 
the  thigh.  These  venae  satellites  adhere  closely  to  the  ar- 
tery, and  are  separated  from  each  other  by  the  latter.  They 
also  have  frequent  anastomoses  with  each  other  across  the 
artery. 

The  Popliteal  Vein  {Vena  Poplitea)  is  a single  trunk 
formed  by'the  union  of  the  anterior,  the  posterior  tibial,  and 
the  fibular  veins.  It  begins  on  the  posterior  part  of  the  head 
of  the  tibia,  and  extends  upwards  through  the  ham  to  the 
perforation  in  the  adductor  magnus  muscle,  which  transmits 
the  femoral  artery.  It  is  situated  on  the  posterior  face  of 


CIRCULATORY  SYSTEM. 


2iii£ 

the  popliteal  artery,  to  which  it  closely  adheres,  and  be- 
hind it,  is  the  popliteal  nerve,  the  continuation  of  the  great 
sciatic. 

The  Femoral  Vein  ( Vena  Femoralis)  is  the  continuation 
upwards  of  the  popliteal;  it  at  first  is  placed  behind  the  ar- 
tery, but  in  a short  space  it  gets  to  its  interior  face,  and 
continues  to  adhere  to  it,  in  that  situation,  up  to  Poupart’s 
ligament,  where  it  becomes  the  external  iliac  vein.  At  the 
usual  distance  below  the  groin,  where  the  arteria  profunda 
is  given  off,  the  femoral  vein  receives  the  vena  cruralis  pro- 
funda, which  is  derived  from  the  branches  of  this  artery, 
and  is  rather  more  superficial  than  it;  the  two  however  ad- 
here closely  together.  Just  below  Poupart’s  ligament  the 
femoral  vein  receives  several  small  branches  of  veins  cor- 
responding with  the  external  pudic  arteries. 

The  Small  Saphena  ( Vena  Saphena  Minor  Externa) 
commences  by  several  small  branches  near  the  external  side 
of  the  top  of  the  foot,  and  the  external  ankle;  a trunk  is 
formed  by  them  behind  the  latter,  which  ascends  along  the 
tendo-achillis  and  the  posterior  face  of  the  gastrocnemius 
muscle,  collecting  several  small  veins  from  the  back  of  the 
leg  in  its  course.  This  vein  is  superficial  in  its  whole  course, 
being  placed  immediately  beneath  the  skin.  In  the  ham, 
it  goes  for  a short  distance  along  the  internal  face  of  the 
popliteal  nerve,  and  then  makes  a dip  through  the  adipose 
matter  there  to  empty  into  the  popliteal  vein. 

It  is  said,  by  Portal,  that  the  branches  of  this  vein  be- 
come very  apparent  in  persons  who  suffer  from  podagra, 
and  from  enlargements  of  the  lymphatic  glands  in  the  ham. 
In  such  case  their  distention  has  been  relieved  by  the  ap- 
plication of  leeches  along  them. 

The  Great  Saphena  ( Vena  Saphena  Magna  Interna)  is 
also  superficial,  has  its  primitive  roots  coming  from  the  in- 
ternal upper  part  of  the  foot,  and  from  the  sole  of  the  latter. 
These  branches  are  assembled  into  a trunk  which  passes  u])- 


VEINS  OP  THE  ABDOMEN. 


263 


wards  in  front  of  the  internal  ankle,  then  ascends  along  the 
internal  face  of  the  leg,  in  a line  corresponding  with  the 
posterior  margin  of  the  tibia.  The  great  saphena  continues 
its  ascent  over  the  internal  condyle  near  its  posterior  part, 
and  then  mounts  up  the  internal  face  of  the  thigh,  in  a line 
corresponding  nearly  with  the  internal  margin  of  the  sar- 
torius  muscle.  It  finally  terminates  in  the  femoral  vein 
about  twelve  or  eighteen  lines  below  Poiipart’s  ligament, 
an  opening  being  left  in  the  fascia  femoris  for  this  purpose. 

In  the  whole  of  this  course  the  great  saphena  is  situated 
between  the  skin  and  the  fascia  of  the  lower  extremity;  it  is 
consequently  so  superficial  that  in  persons  of  moderate  cor- 
pulency it  is  very  visible,  and  by  slight  pressure  above, 
along  with  the  erect  position,  it  becomes  so  much  swollen, 
that  it  is  easily  opened  with  the  lancet  where  it  passes  over 
the  internal  ankle.  It  receives,  in  its  ascent,  small  branches 
from  the  atiterior  and  posterior  part  of  the  leg,  from  the 
corresponding  surfaces  of  the  thigh,  and  near  its  termination 
it  gets  a few  of  the  external  pudendal  veins. 

When  the  great  and  the  small  saphena  veins  are  success- 
fully injected,  their  branches  are  seen  to  form  a considerable 
number  of  anastomoses,  which  thereby  produce  a remark- 
able venous  netwox'k,  just  beneath  the  skin  of  the  whole 
inferior  extremity. 

SECT.  IV. VEINS  OF  THE  ABDOMEN. 

The  External  Iliac  Vein  {Vena  Iliaca  Externa)  being 
the  continuation  of  the  femoral  vein,  passes  into  the  abdo- 
men, under  Poupart’s  ligament,  and  in  contact  with  the  in- 
ternal margin  of  the  external  iliac  artery.  It  there  receives 
the  epigastric,  and  the  circumflex  iliac  veins,  corresponding 
with  the  arteries  of  the  same  name;  it  also  receives  a vein 
of  some  size,  which  enters  by  the  abdominal  canal  in  ad- 
hering to  the  spermatic  chord,  and  which  comes  from  the 
coats  of  the  testicles.*  It  keeps  then  along  the  internal 
side  of  the  artery,  somewhat  behind  it  at  the  superior  mar- 
H.  Cloquet.  Traite  D’Anat, 


264 


CIRCULATORY  SYSTEM. 


gin  of  the  pelvis;  and  joins  the  hypogastric  vein  opposite  to 
the  sacro-iliac  junction,  and  thereby  forms  the  common  iliac 
vein. 

The  Hypogastric  Vein  {Vena  Hypogastrica^  Iliaca  In- 
terna) comes  from  the  inferior  part  of  the  pelvis  in  front  of 
the  sacro-iliac  junction,  and  in  company  with  the  hypogas- 
tric artery.  It  arises  by  branches  corresponding  with  the 
distribution  of  the  latter  to  the  viscera  of  the  pelvis,  and  to 
its  external  parts;  these  branches  are  so  numerous  at  parti- 
cular points  and  have  such  frequent  anastomoses  that  they 
are  often  named  Plexus.  Thus  there  is  a hemorrhoidal 
plexus  for  the  lower  part  of  the  rectum,  a vesical  for  the 
bladder,  a sacral  for  the  sacrum,  a pudendal  for  the  parts  of 
generation  in  the  male;  and  a vaginal  for  the  vagina,  and 
a uterine  for  the  uterus  of  the  female.. 

The  Plexus  Hemorrhoidalis,  besides  being  connected 
with  the  hypogastric,  also  anastomoses  with  the  vena  por- 
tarum. 

The  Plexus  Vesicalis  is  different  in  the  two  sexes.  In 
man  it  commences  at  the  extremity  of  the  penis  by  several 
branches,  which  unite  into  two  trunks  of  considerable  size, 
the  Venae  Dorsales  Penis.  The  latter  go  along  the  upper 
face  of  the  penis,  near  or  at  its  middle,  to  the  symphysis  of 
the  pubes,  continually  receiving  in  this  course  small  trunks 
from  the  integuments  of  the  penis  and  from  the  scrotum. 
They  then  get  into  the  pelvis  between  the  root  of  the  penis 
and  the  symphysis  pubis,  and  continue  horizontally  back- 
wards on  the  side  of  the  prostate  gland,  of  the  vesiculae  se- 
minales,  and  of  the  lower  fundus  of  the  bladder.  They 
receive  many  branches  from  these  parts,  which,  with  the 
frequency  of  the  anastomoses  about  here,  constitute  the 
vesical  plexus.  The  latter  finally  discharges  into  the  lower 
part  of  the  hypogastric  vein  by  two  or  more  branches. 

In  the  female  the  vesical  plexus  begins  on  the  dorsum  of 
the  clitoris,  by  several  branches  coming  from  it  and  from 
the  vulva,  they  get  into  the  pelvis  under  the  symphysis 
pubis  and  on  the  sides  of  the  urethra  and  of  the  vagina, 


VEINS  or  THE  ABDOMEN. 


2G5 


forming  upon  the  lower  part  of  the  bladdei',  and  on  the  side 
of  the  vagina,  with  the  assistance  of  branches  from  these 
viscera,  a remarkable  plexus,  which  also  empties  into  the 
internal  iliac  vein. 

The  Plexus  Sacralis  consists  in  an  order  of  veins  anasto- 
mosing freely  with  each  other,  and  corresponding  with  the 
middle  and  the  lateral  sacral  veins.  They  communicate 
with  the  inferior  end  of  the  vertebral  sinuses  through  the 
anterior  sacral  foramina;  they  also  communicate  with  the 
hemorrhoidal  and  with  the  vesical  veins.  They  terminate 
in  the  venous  trunks  nearest  the  origin  of  the  arteries  from 
which  they  are  derived. 

The  Plexus  Pudendalis  is  derived  from  the  branches  of 
the  internal  pudic  vein  which  go  to  the  perineum,  to  the 
posterior  part  of  the  scrotum,  and  to  the  integuments  of  the 
under  part  of  the  penis.  The  trunk  formed  by  the  as- 
sembling of  these  several  ramifications,  follows  the  course 
of  the  artery  to  which  it  belongs,  and  gets  into  the  pelvis 
at  the  lower  part  of  the  sciatic  foramen,  where  it  contributes 
to  the  formation  of  the  hypogastric  vein. 

The  Plexus  TJterinus  consists  in  a considerable  number 
of  veins,  which  are  distributed  upon  the  surface,  and  in  the 
texture  of  the  uterus;  they  are  also  found  in  abundance  in 
the  broad  ligaments,  where  they  anastomose  with  the  ova- 
rian veins. 

The  Plexus  Vaginalis  comes  from  the  anterior  parts  of 
the  organs  of  generation  constituting  the  vulva,  as  the  labia 
majora,  minora,  and  so  on.  It  also  arises  from  the  whole 
surface  of  the  vagina,  surrounds  it  completely,  and  anasto- 
moses with  the  uterine  veins. 

The  Gluteal,  the  Obturator,  and  the  Ilio-Lumbar  Veins, 
also  contribute  to  the  Hypogastric;  their  description  con- 
forms so  nearly  to  that  of  the  corresponding  arteries,  that 
it  is  unnecessary  to  detail  it. 

ThePrimitive  Iliac  Vein;  ( Vena  Iliaca Primitiva,  Com- 
munis,) formed  by  the  junction  of  the  External  and  of  the 
Internal  Iliacs,  extends  from  the  sacro-iliac  symphysis  to 
VoL.  II.— 34 


26G 


CIRCULATORY  SYSTEM. 


the  lower  margin  of  the  fourth  lumbar  vertebra  on  its  right 
side,  where  it  joins  the  corresponding  trunk  of  the  opposite 
side  of  the  body,  to  form  the  commencement  of  the  ascend- 
ing vena  cava.  In  this  course  the  left  one  passes  obliquely 
across  the  body  of  the  fifth  lumbar  vertebra,  and  beneath 
the  right  primitive  iliac  artery. 

The  Vena  Cava  Inferior  is  situated  on  the  front  of  the 
spinal  column,  to  its  right  side,  and  extends  from  the  lower 
part  of  the  fourth  lumbar  vertebra,  or,  in  other  words,  from 
the  junction  of  the  primitive  iliac  veins  to  the  under  end  of 
the  right  auricle  of  the  heart,  into  which  it  empties.  It  is 
larger  than  the  Descending  Cava. 

In  its  ascent  it  inclines  very  gradually  to  the  right  side  of 
the  spine,  so  as  to  reach  the  opening  in  the  tendinous  centre 
of  the  Diaphragm,  through  which  it  passes,  just  before  it 
terminates  in  the  auricle.  It  is  bounded  on  the  left  side  by 
the  aorta;  and  above  the  latter  it  is  in  front  of  the  left  pillar 
of  the  diaphragm.  Its  lower  extremity  is  crossed  in  front 
by  the  root  of  the  primitive  iliac  artery;  it  is  also  crossed 
in  its  ascent  by  the  duodenum  and  the  pancreas.  Its  upper 
extremity  is  behind  the  liver,  and  frequently  passes  through 
the  substance  of  this  viscus. 

It  receives  the  middle  sacral,  the  lumbar,  the  spermatic, 
the  emulgent,  the  capsular,  the  hepatic,  and  the  phrenic 
veins. 

The  Middle  Sacral  Vein  {Vena  Sacra  Media)  forms,  as 
has  been  just  mentioned  in  the  account  of  the  branches  of 
the  hypogastric  vein,  a part  of  the  sacral  plexus.  Its  trunk 
follows  the  course  of  the  middle  sacral  artery  on  the  front 
of  the  sacrum,  and  discharges  into  the  commencement  of 
the  vena  cava,  in  the  fork  formed  by  the  origin  of  the  pri- 
mitive iliacs. 

The  Lumbar  Veins  {Vense  Lumbales)  correspond  with 
the  lumbar  arteries,  and  are  commonly  four  or  five  in  num- 
ber on  each  side.  Their  primitive  roots  anastomose  with 


VEINS  OP  THE  ABDOMEN. 


267 


the  epigastric,  the  last  intercostal,  and  the  circumflex  iliac 
veins;  the  dorsal  branches  of  them  also  anastomose  with 
the  vertebral  sinuses,  through  the  intervertebral  foramina. 
Their  trunks  pass  along  with  the  arteries,  between  the  bo- 
dies of  the  vertebrse  and  the  psoas  magnus  muscle,  or 
through  the  fasciculi  of  the  latter;  those  on  the  left  side 
pass  behind  the  aorta,  in  order  to  reach  the  vena  cava,  and 
are  consequently  longer  than  such  as  are  on  the  right. 

The  Spermatic  Veins  Spermaticse.)  The  right 

one  extends  from  the  testicle,  to  the  ascending  cava  just  be- 
low the  emulgent  veins;  while  the  one  on  the  left  empties 
into  the  left  emulgent  vein.  They  are  larger  than  the  cor- 
responding arteries,  and  present  some  peculiarities  in  the 
two  sexes. 

In  the  male,  the  extremities  of  these  veins  begin  in  the 
testicle,  and  issue  from  it  through  the  tunica  albuginea; 
some  of  them  also  arise  from  the  epididymis.  They  anas- 
tomose with  the  superficial  veins  of  the  penis  and  of  the 
scrotum,  and  disengaging  themselves  from  the  tunica  vagi- 
nalis, at  its  back  part,  are  assembled  into  four  or  five  anas- 
tomosing trunks,  which  envelop  the  vas  deferens  and  the 
spermatic  artery,  and  compose  a principal  part  of  the  bulk 
of  the  chord.  Having  passed  through  the  abdominal  ca- 
nal, they  are  reduced  on  each  side  to  one  trunk,  which 
creeps  along  the  spermatic  artery,  on  the  front  of  the  psoas 
magnus  muscle,  and  in  company  with  the  ureter.  Some- 
what below  the  kidney,  the  spermatic  vein  is  again  resolved 
into  a sort  of  plexus,  having  frequent  additions  from  the 
veins  in  the  adipose  substance  of  the  kidney,  and  also  some 
from  the  branches  of  the  vena  portarum  in  the  mesentery 
and  in  the  mesocolon.  It  then  is  reduced  once  more  into 
a single  trunk,  which  terminates  as  mentioned.  The  term 
Corpus  Pampiniforme  (vine-like)  is,  by  some  anatomists, 
limited  to  the  last  plexus  formed  by  each  spermatic  vein, 
but  it  is  also  frequently  extended  to  both.* 

In  the  female  the  spermatic  vein  is  not  so  large  as  in  the 


■*  H.  Cloquet.  Trat.  D’Anat, 


263 


CIRCULATORY  SYSTEM. 


male;  it  comes  from  the  ovarium  and  from  the  side  of  the 
uterus,  and  is  joined  by  some  small  branches  from  the 
round  ligament  of  the  uterus,  and  from  the  Fallopian  tube. 
Passing  outwardly  between  the  laminae  of  the  broad  liga- 
ment of  the  uterus,  it  crosses  the  external  iliac  artery,  and 
in  the  subsequent  part  of  its  course  is  disposed  of  as  in  the 
male. 

The  Emulgent  Veins  {Vense  Emulgentes,  Renales')  are 
commonly  two  in  number,  one  on  each  side,  and  extend  ho- 
rizontally from  the  fissure  of  the  kidneys  to  the  ascending 
cava.  They  are  of  a considerable  size,  and  owing  to  the 
position  of  the  vena  cava,  the  left  is  much  longer  than  the 
right,  and  crosses  in  front  of  the  aorta.  They  open  on 
their  respective  sides  of  the  cava  opposite  to  each  other. 
The  branches  of  which  the  emulgent  vein  is  composed, 
coming  from  the  ramifications  of  the  corresponding  artery 
in  the  kidney,  assemble  into  the  single  trunk  near  the  fissure 
of  the  kidney,  this  trunk  is  joined  by  some  small  veins 
from  the  adjacent  adipose  matter  and  from  the  capsulas  re- 
nales, and  on  the  left  side,  as  mentioned,  it  is  also  joined 
by  the  spermatic  vein. 

) 

The  Capsular  Veins  i^Vense  Capsulares)  arise  from  the 
arteries  spent  upon  the  capsulai  renales;  and  are  two  in 
number,  one  on  each  side.  That  on  the  right  discharges 
into  the  vena  cava,  while  the  one  on  the  left  empties  into 
the  left  emulgent  frequently. 

The  Hepatic  Veins  {Venae  Hepaticse)  take  their  rise  in 
the  liver,  and  collect  into  three  principal  trunks,  which 
converging  towards  the  ascending  cava,  discharge  them- 
selves into  it  where  it  adheres  to  the  posterior  margin  of  the 
liver,  immediately  below  the  diaphragm.  Two  of  these 
trunks  come  from  the  right  lobe,  and  one  from  the  left; 
moreover,  there  are  several  small  hepatic  veins  which  dis- 
charge themselves  into  the  cava,  and  come  principally  from 
the  Lobulus  Spigelii. 


THE  VENA  PORTARUM. 


269 


The  Inferior  Phrenic  Veins  {Vense  Phrenicae  Inferio- 
res)  come  from  the  diaphragm,  from  the  corresponding  ar- 
teries. They  are  two  in  number,  and  discharge  into  the  as- 
cending cava  just  above  the  hepatic  veins. 

SECT.  V. OF  THE  VENA  PORTARUM. 

The  Vena  Portarum  is  derived  from  the  viscera  of  the 
abdomen,  and  presents  the  singularity  of  a vein  ramifying 
through  a gland,  the  liver,  before  its  blood  is  returned  to 
the  general  circulation.  The  arteries  from  which  it  draws 
its  supply  of  blood  are  the  superior  and  the  inferior  mesen- 
teric, and  the  coeliac  with  the  exception  of  its  hepatic  branch. 
The  viscera  of  the  abdomen,  which  contribute  to  it,  are  the 
spleen,  the  stomach,  the  gall-bladder,  the  pancreas,  the 
small  intestines,  the  large  and  the  small  omentum. 

a.  The  Splenic  Vein  {Vena  Splenica')  is  formed  by  se- 
veral branches,  which  coming  out  distinctly  from  the  fissure 
of  the  spleen,  unite  after  a short  course  into  a single  trunk. 
This  trunk  runs  in  company  with  the  splenic  artery,  below 
it,  along  the  superior  margin  of  the  pancreas,  is  not  quite 
so  tortuous  as  the  artery  itself,  and  proceeding  from  left  to 
right,  is  joined  to  the  superior  mesenteric  vein  in  front  of 
the  vertebral  column. 

In  this  course  the  splenic  receives  the  small  veins*  ( Vense 
Breves)  corresponding  with  the  vasa  brevia  of  the  great 
end  of  the  stomach,  and  then,  successively,  several  branches 
from  the  pancreas.  It  likewise  i-eceives  the  gastric,  or  the 
superior  coronary  vein  of  the  stomach,  the  right  gastro- 
epiploic, and  the  left  gastro-epiploic  of  the  same  viscus,  all 
of  which  correspond  with  the  arteries  distributed  to  the 
latter. 

b.  The  Inferior  Mesenteric  Vein  {Vena  Meseraica  In- 
ferior) corresponds  with  the  inferior  mesenteric  artery,  and 
consequently  derives  its  primitive  branches  from  the  rec- 

* M.  Bauer  discovered,  in  1824,  valves  in  these  vessels,  contrary  to  the 
general  analogy  of  the  system  of  the  Vena  Portarum.  His  obsen'ations 
have  been  confimed  by  H.  Cloquet, 


270 


CIRCULATORY  SYSTEM. 


turn  by  the  upper  hemorrhoidal  veins,  which  anostomose 
with  the  lower;  from  the  sigmoid  flexure  of  the  colon,  and 
from  the  left  descending  portion  of  the  latter.  The  trunk 
formed  by  these  branches,  ascends  behind  the  peritoneum, 
between  the  ureter  and  the  aorta,  and  going  up  behind  the 
pancreas,  is  discharged  into  the  splenic  vein  an  inch  or  two 
from  its  termination.  But  like  the  veins  belonging  to  the 
lesser  curvature,  and  the  right  side  of  the  stomach,  it  some- 
times empties  directly  into  the  vena  portarum,  or  into  the 
upper  end  of  the  superior  mesenteric. 

c.  The  Superior  Mesenteric  Vein  ( Vena  Meseraica  Su- 
perior) is  the  largest  of  the  trunks  which  contribute  to  form 
the  vena  portarum.  It  is  derived  from  the  ramifications  of 
the  superior  mesenteric  artery  upon  the  small  intestines,  the 
ileo-coiic  valve,  the  right  ascending,  and  the  transverse  co- 
lon. Its  branches  constitute  in  the  mesentery  and  the  me- 
socolon a vascular  intertexture,  forming  arches  and  meshes 
adhering  to  the  corresponding  ones  of  the  arteries.  In  the 
transverse  mesocolon  it,  like  the  artery,  anastomoses  with 
the  inferior  mesenteric  vein.  Its  trunk  being  formed  by 
the  union  of  these  several  branches,  ascends  the  mesentery, 
and  goes  in  front  of  the  duodenum,  where  the  latter  crosses 
the  spine;  immediately  afterwards  it  gets  behind  the  pan- 
creas and  near  its  right  end  is  joined  by  the  splenic  vein. 
It  here,  also,  receives  small  branches  from  the  duodenum, 
from  the  pylorus,  and  from  the  gall-bladder. 

The  trunk  of  the  vena  Portarum  being  formed  behind 
the  pancreas  by  the  union  of  the  inferior  mesenteric  with 
the  splenic  vein,  extends  from  this  point  to  the  transverse 
fissure  of  the  liver,  and  is  about  four  inches  in  length.  It 
ascends  obliquely  from  left  to  right,  behind  the  second  cur- 
vature of  the  duodenum,  being  bounded  on  the  right  side 
by  the  biliary  ducts,  and  on  the  left  by  the  hepatic  artery, 
where  it  is  surrounded  by  a great  many  nervous  filaments 
and  lymphatic  vessels,  with  all  of  which  it  is  united  by  a 
common  envelope  of  cellular  substance,  and  of  peritoneum, 
called  the  capsule  of  Glisson.  Having  reached  the  trans- 


PECULIARITIES  OE  THE  ECETUS. 


271 


verse  fissure  of  the  liver  it  divides  into  two  branches,  which 
are  each  at  a right  angle  to  it,  but  in  line  with  one  another; 
they  constitute  the  Sinus  Portarum,  of  which,  the  right 
branch  being  spent  upon  the  great  lobe,  and  the  left  upon 
the  small  lobe  of  the  liver,  are  ramified  to  infinity  through 
the  structure  of  the  latter.  The  terminating  branches  of 
the  vena  portarum  empty  into  the  veiias  hepaticae. 

Several  cases  are  recorded  in  the  annals  of  anatomy  in 
which  the  vena  portarum,  instead  of  going  into  the  liver, 
discharged  immediately  into  the  ascending  cava.*  In  such 
instances  the  hepatic  artery  is  much  larger  than  usual.  Ac- 
cording to  J.  F.  Meckel,  notwithstanding  they  are  anoma- 
lies, yet  as  in  most  other  cases  of  deviation  from  the  gene- 
ral type  of  the  human  family,  a striking  analogy  may  be 
found  between  them  and  what  occurs  in  some  of  the  lower 
orders  of  animals.  Here  the  analogy  exists  with  the  inver- 
tebrated  animals. 


CHAPTER  IV. 

OF  THE  PECULIARITIES  IN  THE  CIRCULATORY  SYSTEM 
OF  THE  FOETUS. 

Owing  to  the  want  of  respiration  in  the  foetus,  its  circu- 
lation IS  conducted  in  a manner  very  difierent  from  that  of 
the  adult.  Moreover,  its  parasitical  life  requires  an  alli- 
ance, through  the  organs  of  circulation,  with  the  mother. 
Its  peculiarities,  therefore,  may  be  studied  under  two  heads: 
those  which  arise  from  the  want  of  respiration,  and  those 
which  are  required  for  its  nourishment.  The  peculiarities 
of  the  first  order  are  situated  in  the  thorax,  and  those  of 
the  second  in  the  abdomen. 

* Lieutaud,  Hist.  Anat.  Med.  Huber,  Obs.  Anat.  p.  34.  Abernethy, 
Ph.  Tr.  1793,  part  i.  Lawrence,  Med.  Ch.  Trans,  vol.  v. 


CIRCULATORY  SYSTEM- 


SECT.  I. OF  THE  PECULIARITIES  OF  THE  FIETUS  ARISING 

FROM  THE  WANT  OF  RESPIRATION. 

The  Heart,  at  a very  early  period  after  conception,  so 
early  as  about  the  end  of  the  first  month,  is  sufficiently  de- 
veloped to  be  in  a state  of  great  activity.  The  first  indi- 
cation of  its  existence,  and  indeed  of  the  life  of  the  new 
animal,  is  a small  tremulous  point  called  the  Punctum  Sa- 
liens,  from  its  incessant  motion.  The  muscular  structure 
of  it  is  soon  evolved,  and  in  a few  months  becomes  very 
manifest.  At  the  earliest  visible  period  of  the  heart  in  the 
incubated  egg,  which  affords  a satisfactory  analogy,  it  con- 
sists of  two  vesicles  united  by  a canal,  (Canalis  Auricula- 
ris  of  Haller.)  One  of  the  vesicles  is  the  right  auricle; 
the  other  is  the  left  ventricle,  and  is  probably  the  first  to 
pulsate.  The  aorta  is  also  visible,  as  well  as  the  ven$  cavas. 
The  circulation,  at  this  period,  is  very  simple;  the  blood 
starting  from  the  left  ventricle  is  propelled  into  the  aorta; 
it  is  collected  from  the  ramifications  of  the  last  into  the  two 
vense  cavse,  and  thereby  brought  to  the  right  auricle;  it  is 
then  propelled  by  the  right  auricle  through  the  canalis  au- 
ricularis  into  the  left  ventricle,  whereby  its  round  is  com- 
pleted, and  then  starts  again.  This  is  the  most  simple  kind 
of  circulation,  and  is  found,  in  fact,  during  the  whole  lives 
of  such  animals  as  do  not  breathe  by  lungs,  for  example, 
fish.  As  the  gills  in  them  take  the  place  of  lungs,  a branch 
from,  the  aorta,  spent  upon  the  gills,  is  sufficient  for  their 
purposes  of  respiration. 

The  terms  right  auricle  and  left  ventricle  have  been  used, 
because  the  cavities  alluded  to  perform  the  functions  of  the 
adult  state;  but  in  the  progress  of  the  development  of  the 
heart,  a partition  begins  to  show  itself  which  ultimately  di- 
vides each  of  them  into  two  distinct  compartments,  where- 
by we  have  a right  auricle  and  a left  one,  a left  ventricle 
and  a right  one.  And  the  canalis  auricularis  is  reduced 
from  a canal  into  a short  orifice  called  ostium  venosum,  com- 
municating from  the  auricles  to  the  ventricles,  and  which 


PECULIARITIES  OF  THE  F(ETUS. 


273 


is  afterwards  divided  into  two,  one  for  either  side  of  the 
.heart.  The  partition  between  the  ventricles  is  completed 
about  the  end  of  the  second  month  of  gestation,  at  a period 
when  the  aorta,  from  having  been  simple  originally,  is  con- 
verted into  two  canals,  one  of  which  becomes  the  pulmona- 
ry artery.  The  partition  between  the  auricles  is  not  com- 
pleted till  birth.  In  cases  of  monstrosity,  it  is  interesting 
to  see  how  much  the  heart,  at  the  end  of  uterine  life,  has 
still  preserved  this  original  type  of  simplicity.  I have  late- 
ly dissected  a double  foetus,  where,  from  the  parasitical  cha- 
racter of  one,  no  effort  had  been  made  for  the  development 
of  the  lungs  of  the  latter.  The  consequence  of  which  was, 
the  parasite’s  heart  consisted  only  of  the  right  auricle  and 
of  the  left  ventricle,  and  the  pulmonary  artery  had  not  been 
formed  at  all,  there  being  but  the  single  tube,  the  aorta; 
which  led  from  the  left  ventricle,  and  had  a sort  of  arrange- 
ment in  its  branches  depending  upon  the  tendency  to  form 
pulmonary  arteries.* 

At  birth,  the  auricular  septum  has  advanced  so  far  that 
the  communication  between  the  cavities  is  kept  up  only  by 
a deficiency  called  the  Foramen  Ovale.  This  foramen, 
marked  by  a depression  on  the  right  side,  admits  a small 
quill  when  conducted  obliquely  through  it,  and  is  protected 
on  the  left  side  by  a valve,  the  edge  of  which  is  upwards, 
and  which,  when  applied,  is  just  large  enough  to  cover  the 
whole  foramen.  The  moment  that  the  blood  ceases  to  pass 
through  the  foramen  ovale,  which  occurs  at  the  first  act  of 
inspiration,  the  valve  is  applied,  and  the  aperture  grows  up 
by  the  adhesion  of  its  edge.  The  mechanism  of  this  pro- 
cess is  sufficiently  simple.  So  long  as  the  principal  current 
of  blood  was  into  the  right  auricle,  the  valve  was  pushed 
oflf  from  the  side  of  the  septum ; but  as  breathing  esta- 
blishes, through  the  lungs,  pulmonary  veins,  and  left  au- 
ricle, a current  of  circulation  equivalent,  both  in  quan- 
tity and  force,  to  that  through  the  two  venae  cavae  and 
right  auricle;  a perfect  equilibrium  between  the  auricles 

* For  a detail  of  this  case,  see  North  American  Medical  and  Surgical 
Journal,  Philad.  Oct.  1826. 

VoL.  II.— 35 


274 


CIRCULATORY  SYSTEM. 


is  established,  and  the  valve  retains  its  place  against  the 
septum.  Notwithstanding  the  incessant  action  of  the  auri- 
cles during  all  the  subsequent  periods  of  life,  this  equili- 
brium, in  the  force  and  time  of  their  contraction,  is  never 
departed  from.  A circumstance  proved  conclusively  by  the 
health  and  strength  of  adults  in  whom  the  valve  has  never 
adhered  to  the  day  of  their  death;  an  observation  made  by 
many  anatomists,  and  of  which  I have  witnessed  several 
examples;  in  one  of  them  I passed  two  fingers  readily  from 
one  auricle  into  the  other,  owing  to  the  unusual  size  of  the 
aperture. 

The  valve  which  closes  the  foramen  ovale  is,  first  of  all, 
scarcely  perceptible;  but  as  the  foetus  advances  in  age,  it 
also  advances  in  size,  and  is,  indeed,  large  enough  to  close 
the  foramen  some  weeks  before  birth.  It  is  formed  from 
the  lining  membrane  of  the  two  auricles  with  some  inter- 
mediate substance. 

The  Valve  of  Eustachius,  which  exists  also  in  the  adult 
heart,  is  placed  at  the  anterior  semi-circumference  of  the 
orifice  of  the  ascending  vena  cava  in  the  right  auricle,  one 
of  its  ends  adhering  to  the  anterior  margin  of  the  foramen 
ovale.  This  valve,  contrary  to  the  one  in  the  foramen 
ovale,  is  larger  in  proportion  as  the  foetus  is  younger,  and, 
when  first  observed,  covers  the  whole  orifice  of  the  vena 
cava  ascendens;  its  opening,  however,  is  in  the  direction  of 
the  current  of  blood  in  the  latter.  It  also  is  formed  by  a 
duplicature  of  the  lining  membrane  of  the  auricle,  and,  from 
its  disposition,  determines  the  blood  of  the  ascending  cava 
to  flow  through  the  foramen  ovale  into  the  left  auricle,  ei- 
ther wholly  or  in  part,  according  to  the  period  of  gestation. 
Its  obliquity  also  gives  a direction  to  the  blood  of  the  de- 
scending cava,  into  the  right  ventricle  from  the  right  au- 
ricle. These  uses  of  the  Eustachian  valve  were  pointed 
out  by  the  celebrated  Sabatier;*  their  value  will  be  illus- 
trated hereafter. 

The  Ventricles  of  the  Heart,  at  birth,  have  the  same 
'*  Traite  d’Anat.  vol.  it  p.  296. 


PECULIARITIES  OP  THE  FCETUS. 


275 


structure  and  internal  arrangement  as  afterwards;  they  are 
remarkable,  however,  for  being  of  equal  thickness,  or  nearl}'’ 
so,  an  observation  of  Mr.  John  Hunter.*  This  fact  is  con- 
nected with  the  circumstance  of  their  both  contributing  to 
the  aortic  circulation  till  respiration  begins,  owing  to  the 
pulmonary  artery  entering,  during  foetal  life,  by  its  largest 
branch,  into  the  aorta. 

The  Ductus  Arteriosus  constitutes  this  branch  of  the  pul- 
monary artery,  and  is,  in  fact,  the  continuation  of  the  trunk 
of  the  latter  into  the  aorta,  immediately  behind  the  origin 
of  the  left  subclavian  artery.  The  right  and  the  left  pulmo- 
nary arteries,  at  this  period,  are  but  inconsiderable  trunks, 
incapable  by  any  means  of  carrying  off  all  the  blood  of  the 
right  ventricle;  the  greater  part  of  it  therefore  is  conveyed 
by  the  ductus  arteriosus  into  the  descending  aorta.  As  the 
contraction  of  the  ventricles,  like  that  of  the  auricles,  is 
synchronous,  it  is  evident  that  the  column  of  blood  in  the 
descending  aorta,  is  acted  upon  by  both  ventricles  at  the 
same  moment. 

The  ductus  arteriosus,  preserves  the  principle  of  a sin- 
gle circulation  in  the  foetus;  which  was  first  of  all  mani- 
fested by  the  two  ventricles,  constituting  but  one  cavity; 
and  by  the  aorta  arid  pulmonary  artery  being  but  one 
trunk.  At  the  first  act  of  inspiration  the  lungs,  which  were 
before  solid,  and  the  thorax,  which  was  compressed,  are 
greatly  augmented  in  volume  by  the  introduction  of  air. 
The  dilatation  of  the  thorax,  besides  introducing  air  through 
the  trachea,  causes  an  increased  flow  of  blood  through  the 
right  and  left  pulmonary  arteries,  in  order  to  fill  the  va- 
cuum in  the  lungs.  The  pulmonary  arteries  become  in  that 
way  permanently  dilated,  and  the  circulation  is  finally 
drawn  off  entirely  from  the  ductus  arteriosus,  though  this 
takes  several  weeks  or  months  before  it  is  completely  ac- 
complished. The  ductus  arteriosus  in  this  time  is  conti- 
nually contracting,  and  is  at  length  converted  into  a liga- 


Animal  (Economy. 


270 


CIKCULATOKy  STSTjEM. 


mentous  chord,  like  other  arteries,  whose  circulation  has 
been  arrested. 

These  are  the  several  peculiarities  which  distinguish  the 
foetal  circulation,  owing  to  the  privation  of  respiration;  and 
it  is  clear,  that  the  collective  result  is  that  of  a circulation 
quite  as  simple  as  if  the  heart  consisted  of  but  two  cavities; 
while,  at  the  same  time,  it  keeps  this  organ  in  a state  of 
preparation  for  carrying  on  two  distinct  circulations,  one 
pulmonary  and  the  other  aortic,  from  the  moment  that  re- 
spiration begins;  so  that  the  whole  mass  of  blood  is,  in  sub- 
sequent life,  brought  successively  under  the  influence  of 
respiration,  by  having  to  pass  unavoidably  through  the 
lungs. 

SECT.  II. OP  THE  PECULIARITIES  OP  THE  CIRCULATION  OP 

THE  P(ETUS  CONNECTED  WITH  ITS  NOURISHMENT. 

The  Umbilical  Vein,  one  of  the  constituents  of  the  umbi- 
lical chord,  brings  the  blood  from  the  placenta  to  the  foetus. 
This  vessel  is  from  three  to  four  lines  in  diameter,  and  enters 
at  the  navel;  thence  it  goes  along  the  loose  margin  of  the 
suspensory  ligament  of  the  liver,  and  traverses  the  anterior 
half  of  the  umbilical  fissure,  to  terminate  in  the  left  branch 
of  the  sinus  of  the  vena  portarum.  In  this  course  through 
the  liver,  the  umbilical  vein  sends  oflf  to  the  right  and  left 
lobes,  several  small  branches.  As  the  intestinal  circulation 
of  the  foetus  is  too  small  to  send  much  blood  through  the 
vena  portarum,  if  would  be  sufficiently  correct  to  consider 
the  sinus  vense  portarum  as  the  bifurcation  of  the  umbilical 
vein,  but,  as  this  might  introduce  a confusion  into  the  de- 
scription, it  will  be  better  to  retain  the  adult  nomenclature. 

The  Ductus  Venosus  is  a vein  which  occupies  the  poste- 
rior half  of  the  umbilical  fissure,  and  is  about  a line  and  a 
half  in  diameter.  It  arises  from  the  left  branch  of  the  sinus 
portarum,  opposite  to  the  place  where  the  umbilical  vein 
entered  or  terminated,  and  is  consequently  in  the  same  line 


CIRCULATION  OF  THE  FffiTUS. 


277 


with  the  latter.  Traversing  the  posterior  part  of  the  umbili- 
cal fissure,  it  terminates  in  the  left  vena  cava  hepatica,  as 
this  vein  is  about  joining  the  ascending  cava,  just  below  the 
tendinous  centre  of  the  diaphragm.  Through  this  rout  much 
of  the  blood  of  the  umbilical  vein  is  carried  directly  to  the 
right  auricle  of  the  heart,  and  then  passed  through  the  fora- 
men ovale  into  the  left  auricle  by  the  mechanism  of  the 
Eustachian  valve. 

From  these  considerations,  it  is  evident  that  the  umbili- 
cal vein  really  performs  the  office  of  a vein  till  it  reaches 
the  liver,  but  that  there  much  of  its  blood  is  spent  through 
the  portal  circulation,  upon  the  nourishment  of  this  viscus, 
and  that  what  remains  is  carried  through  the  ductus  venosus 
to  the  heart.  Like  other  veins,  it  is  furnished  with  valves, 
of  which  there  are  two:  one  at  its  termination  in  the  sinus 
portarum,  and  the  other  at  the  cardiac  extremity  of  the 
ductus  venosus.*  The  establishment  of  respiration,  by 
putting  the  circulation  into  other  channels,  likewise  causes 
its  obliteration  and  final  conversion  into  a ligamentous  chord. 
The  valve,  at  the  sinus  portarum,  prevents  the  blood  from 
taking  a retrograde  course,  and  thereby  keeping  the  um- 
bilical vein  open;  the  valve  of  the  ductus  venosus  has  the 
same  effect  upon  the  duct  to  which  it  belongs,  and  is  aided 
by  the  current  of  blood  in  the  left  sinus  portarum,  setting 
across  the  mouth  of  the  ductus  venosus  instead  of  plunging 
into  it  from  the  umbilical  vein,  as  in  foetal  life. 

It  is  worthy  of  remark,  that  the  left  branch  of  the  sinus 
portarum  is  bounded,  on  its  right  extremity,  by  the  end  of 
the  vena  portarum,  and  receives,  about  its  middle,  the  um- 
bilical vein.  In  the  space,  then,  between  the  umbilical  vein 
and  the  portal,  the  circulation,  from  the  predominance  of 
umbilical  blood  in  foetal  life,  is  conducted  from  left  to  right, 
but  afterwards  from  right  to  left,  as  the  portal  circulation  is 
established  and  the  other  is  arrested. 

The  Umbilical  Arteries  discharge  the  important  office  of 
conducting  the  effete  blood  of  the  fmtus  to  the  placenta. 


Bichat,  Anat.  Descrip,  vol,  v.  p.  419. 


27S 


dlRCUXATORV  SYSTEM. 


They  are  the  continuations  of  the  internal  iliacs,  and  are 
two  in  number,  one  on  either  side;  they  conduct  off  so 
much  of  the  blood  of  the  primitive  iliacs,  as  to  leave  the 
external  iliacs  of  a very  small  size.  During  the  early  months 
of  uterine  life,  they  are  rather  indeed  the  continued  trunks 
of  the  primitive  iliacs,  the  branches  from  the  latter  being 
then  so  little  developed  as  to  appear  quite  subordinate  to 
the  chief  function  of  carrying  the  blood  out  of  the  foetus  to 
the  placenta.  But  as  the  inferior  extremities  and  the  but- 
tocks grow,  these  subordinate  branches  are  more  and  more 
evolved. 

At  birth,  the  upibilical  arteries,  after  dipping  very  su- 
perficially into  the  pelvis,  rise  up  at  the  sides  of  the  bladder 
and  converge  towards  the  navel.  They  emerge  at  the  latter, 
cling  together  and  traverse  the  umbilical  chord  by  twisting 
spirally  around  the  umbilical  vein,  like  two  small  strings 
wound  in  this  way  upon  a larger  one.  Their  diameter  is 
from  a line  to  a line  and  a half.  They  anastomose  as  they 
join  the  placenta,  but  not  previously. 

Like  the  circulation  between  arteries  and  veins  in  other 
parts  of  the  body,  the  capillaries  of  the  umbilical  arteries 
terminate  in  those  of  the  umbilical  vein  in  the  placenta. 
From  the  observations  of  Wrisberg,  Osiander,  and  the 
highly  distinguished  Professor  Chapman  of  the  University 
of  Pennsylvania,  it  seems  that  there  is  no  direct  vascular 
communication  between  the  mother  and  the  foetus. 

This  opinion  is  founded  upon  the  leading  facts,  that  the 
finest  injections  do  not  pass  from  one  to  the  other;  that  foe- 
tuses, after  the  death  of  the  mother  from  haemorrhage,  still 
live  and  retain  their  usual  quantity  of  blood;  that  if  the 
foetus  be  expelled  entire  with  the  placenta,  and  membranes 
unhurt,  the  circulation  still  continues.  One  example  of 
which  was  witnessed  nine  minutes  by  Wrisberg;*  another 
fifteen  by  Osiander;!  some  from  ten  to  twenty  minutes 
by  Professor  Chapman;!  another  for  an  hour  by  Professor 
Channing  of  Boston,  and  Dr.  Selby  of  Tennessee,§  where 
a bath  of  tepid  water  was  used  to  resuscitate  the  foetus.  Also, 

* Meckel,  Man.  D’Anat.  vol.  iii.  p.  163.  f Id. 

± Chapman’s  Med.  and  Phys.  Journal,  vol.  i.  p.  6.  § Id. 


CIRCULATION  OP  THE  POETUS. 


279 


from  the  observations  of  Breschet,  it  seems  that  the  glo- 
bules of  the  blood  of  the  foetus,  when,  inspected  by  the  mi- 
croscope, are  different  in  appearance  from  those  of  the  mo- 
ther. * 

The  effete  blood  of  the  umbilical  arteries  becomes  rege- 
nerated  in  the  placenta,  assumes  a brighter  hue,  and  is  re- 
turned to  the  foetus  by  the  umbilical  vein.  According  to 
the  theory  of  Sabatier  concerning  the  use  of  the  Eustachi- 
an valve,  if  the  latter  did  not  exist,  the  fresh  blood  brought 
to  the  heart  by  the  ductus  venosus,  instead  of  being  divert- 
ed into  the  left  auricle  through  the  foramen  ovale,  would  be 
received  by  the  right  auricle  and  transmitted,  either  wholly 
or  in  a great  degree,  into  the  right  ventricle.  It  would  then 
be  passed  from  the  latter  through  the  pulmonary  artery  and 
ductus  arteriosus  into  the  descending  aorta,  so  that  no  part  of 
the  system,  above  the  junction  of  the  duct  with  the  aorta, 
could  receive  the  benefit  of  it;  this  would  leave  the  head 
and  upper  extremities  unsupplied  with  fresh  blood.  More- 
over, much  of  the  latter  would  be  fruitlessly  introduced, 
for  *it  would  depart  almost  immediately  through  the  um- 
bilical arteries.  But  the  Eustachian  valve  determining  the 
flow  of  blood  of  the  ascending  cava  into  the  left  auricle,  its 
passage  into  the  left  ventricle  is  a matter  of  course;  thence 
it  begins  the  aortic  circulation  fairly,  so  that  every  part  of 
the  system  participates  in  its  benefits. 

The  celebrated  Wistart  has  also  happily  suggested,  that 
without  this  arrangement  the  blood  of  the  coronary  arteries 
of  the  heart  itself,  the  purity  of  which  is  so  essential  to  the 
vigour  of  circulation,  would  otherwise  have  been  effete,  and 
consequently  unfit  for  its  object  of  refreshing  the  heart. 

The  umbilical  arteries  become  the  round  ligaments  of  the 
bladder,  after  the  circulation  through  them  has  ceased,  with 
the  exception  of  their  pelvic  extremities,  which  subsequent- 
ly constitute  the  trunks  of  the  Internal  Iliac  Arteries. 

* Am.  Med.  Jour.  vol.  i.  p.  193. 

t System  of  Anat.  vol.  ii.  p.  76,  3d  edition. 


2S0 


CIRCULATORY  SYSTEM. 


CHAPTER  V. 

OP  THE  GENERAL  ANATOMY  OF  THE  ABSORBENT  SYSTEM. 

The  absorbent  system  is  one  of  the  most  interesting  of 
those  which  compose  the  human  body,  both  on  account  of 
its  very  general  diffusion,  and  of  the  office  of  interstitial 
absorption  that  it  incessantly  carries  on,  thereby  removing 
the  effete  parts  of  the  body  and  making  room  for  the  depo- 
site  of  new  ones.  It  is  also  called  the  lymphatic  system, 
owing  to  the  transparent  colour  of  the  fluid  which  it  con- 
ducts. 

With  the  exception  of  an  imperfect  observation  of  some 
of  these  vessels  in  the  mesentery  of  a goat,  by  Herophilus 
and  Erasistratus,  280  years  before  Christ,  during  the  reigns 
of  the  Ptolemies  in  Egypt,  what  is  known  of  them  is  en- 
tirely a modern  acquisition  in  anatomy.  In  1564,  Eusta- 
chius  discovered  the  thoracic  duct  of  a horse,  which,  in  the 
ignorance  of  its  use,  he  called  vena  alba  thoracis.  This 
fact  remained  insulated  and  almost  forgotten  for  seventy 
years.  In  1622,  Asellius  discovered  the  absorbents  of  the 
mesentery,  and  in  the  discussions  consequent  thereto,  the 
original  observation  of  Herophilus  and  Erasistratus  was 
raised  from  an  oblivion  of  nineteen  centuries,  to  be  again 
brought  to  light  and  admired.  Asellius  seems  to  have  un- 
derstood that  the  absorbents  of  the  mesentery  collect  the 
chyle  from  the  intestines,  but  his  knowledge  ceased  there, 
for  he  thought  that  they  discharged  into  the  vena  porta- 
rum.*  In  1634,  Weslingius  saw  the  thoracic  duct  again; 
and  in  1649,  ascertained  that  the  chyliferous  vessels  of 
Asellius  terminated  in  it.  In  1650,  Olaus  Rudbeck,  a 
young  man  pursuing  his  anatomical  studies  in  Leyden,  saw 

* It  is  somewhat  remarkable,  that  the  celebrated  Harvey,  who  had  him- 
self so  much  to  complain  of,  in  the  obstinacy  with  which  his  cotempora- 
ries adhered  to  ancient  errors,  for  thirty  years  resisted  the  discovery  of 
Asellius,  and  died  finally  protesting  against  it. 


ANATOMT  OF  THE  ABSORBENT  SYSTEM. 


281 


first  the  lymphatic  vessels  of  the  liver,  and  in  a few  months 
afterwards  injected  similar  ones  in  the  loins,  in  the  thorax, 
in  th#groins,  and  in  the  arm-pits.  Thomas  Bartholine,  a 
teacher  of  great  reputation  in  those  days,  in  a dissertation 
dated  in  1652,  claimed  for  himself  the  priority  of  these  ob- 
servations, and  from  the  obscurity  of  Rudbeck,  enjoyed  for 
some  time  the  merit  of  them.  In  1654,  Rudbeck  published 
and  set  forth  his  own  pretensions  with  such  force,  that  he 
finally  triumphed  over  his  antagonist,  but  not  until  the 
whole  world  of  anatomy  had  been  set  in  commotion; 
one  party  being  for  the  professor,  and  the  other  for  the  pu- 
pil; and  many  bloody  strifes  having  arisen  between  the  stu- 
dents of  the  respective  sides.  In  1653,  Jolyff,  a celebrated 
anatomist,  of  London,  proclaimed  his  own  rights  to  this 
warmly  contested  honour,  but  the  period  being  rather  late, 
his  name  is  scarcely  associated  with  the  history  of  these 
feuds.  Almost  a century  then  passed  before  there  were 
many  important  additions  to  the  knowledge  of  those  times. 
After  which  great  contributions  were  made  by  Dr.  A. 
Munro,* * * §  Dr.  W.  Hunter,!  Hewson,!  Cruikshank,§  but 
chiefly  by  the  celebrated  Mascagni,  ||  who  having  imagined 
finely  pointed  instruments  of  glass  for  executing  his  injec- 
tions of  these  vessels,  succeeded  in  demonstrating  them  in 
almost  every  part  of  the  body,  excepting  the  spinal  mar- 
row, the  brain,  the  ball  of  the  eye,  and  the  placenta. 

The  Lymphatic  Vessels  are  small,  pellucid,  transparent, 
cylindrical  tubes,  generally  of  about  a line  or  less  in  dia- 
meter, whose  trunks  have  been  traced  to  all  the  external 
and  internal  surfaces  of  the  body,  and  to  the  depth  of  all 
the  organs,  with  the  exceptions  stated.  It  is  only  very 
lately,  however,  that  their  existence  on  the  external  surface 
of  the  skin  has  been  put  beyond  doubt,  by  the  observations 

* De  Venis  Ljrnph.  Valy.  Berlin,  1757 — 70. 

■j-  Med.  Comment.  London,  1762 — 77. 

i Experimental  Inquiries,  London,  1774 — 77. 

§ Anat.  of  the  Lymphatics,  London,  1774— 90. 

II  Vasor  Lymph.  Corp.  Hum.  Historia  et  Ichnographia,  Sienne.  1787- 
Voj,.  II,— 36 


CIRCULATOKY  SYSTEM. 


oy2 

and  injections  of  M.  Lauth.*  Their  origin  is  so  attenuated, 
that  anatomists  have  come  to  no  satisfactory  conclusion  in 
regard  to  its  manner.  The  earlier  cultivators  of  this  hfranch 
of  study,  not  knowing  their  absorbent  properties,  conceived 
them  to  be  continuations  of  the  arteries  applied  to  the  re- 
conducting of  the  serous  part  of  the  blood  to  the  heart;  and 
considered  the  opinion  substantiated  by  the  circumstance  of 
their  being  occasionally  filled  by  fine  injections  thrown  into 
the  arteries.  More  improved  views  of  their  uses  caused 
the  abandonment  of  this  theory,  and  the  substitution  of 
their  absorbing  powers;  in  which  case  the  minds  of  anato- 
mists became  divided  between  the  ampulla-like  mouth,  or 
wide  patulous  origin  of  Lieberkuhn,  and  the  small  orifices 
of  Hewson.  It  is,  perhaps,  not  possible  to  solve  the  ques- 
tion in  regard  to  the  mode  of  origin  of  the  lymphatics,  at 
least  in  most  parts  of  the  body.  Meckel,  about  the  middle 
of  the  last  century,  asserted  their  continuity  with  the  veins. 
Mr.  Ribes  has  seen  matter  injected  into  the  vena  portarum 
find  its  way  into  the  lymphatics  of  the  liver. 

On  this  subject  M.  Chaussier  says,t  that,  ignorant  of 
the  rpanner  in  which  the  arteries,  veins,  nerves,  and 
lymphatics,  arrange  themselves  collectively  into  a glandu- 
lar structure,  or,  in  other  words,  into  a capillary  system, 
we  cannot  avoid  ignorance  of  the  part  acted  by  the  lym- 
phatics alone;  we  only  know  that  the  minute  lymphatics 
form  a portion  of  the  elements  of  each  viscus  and  structure 
of  the  body,  and  that  they  only  become  visible  in  becoming 
larger  trunks. 

The  absorbents,  in  proceeding  from  their  origins,  in  ge- 
neral become  larger  and  less  numerous,  and  form  frequent 
anastomoses  with  one  another.  The  proportionate  increase 
of  magnitude  from  the  successive  junction  of  trunks  is,  how- 
ever, by  no  means  equal  to  what  occurs  in  the  veins.  The 
larger  superficial  absorbent  trunks  of  the  extremities  have 
not  so  much  disposition  to  run  into  one  another,  whence 
they  retain  a size  almost  uniform  from  one  end  of  the  limb 

♦ Essai  sur  les  Vaisseaux  Lymph.  Strasburg,  1824.  . 

■f  Diet,  des  Sciences  Med.  Art.  I.ymphatics. 


ANATOMY  OP  THE  ABSORBENT  SYSTEM. 


283 


to  the  other.  When  fully  distended,  the  appearance  of  ab- 
sorbents is  not  regularly  cylindrical,  but  knotted,  owing  to 
the  frequent  valvular  interruptions  to  their  cavities.  The 
absorbents,  from  all  parts  of  the  body,  are  finally  united 
into  two  trunks;  one  on  the  left,  and  the  other  on  the  right 
side  of  the  trunk  of  the  body,  and  which  discharge  their 
contents  into  the  venous  system,  each  on  its  respective  side, 
at  the  junction  of  the  internal  jugular  and  subclavian  vein. 
The  trunk  on  the  right  side  receives  the  lymphatics  of  the 
right  side  of  the  head  and  neck,  of  the  right  lung,  and 
right  superior  extremity;  while  the  trunk  on  the  left,  called 
the  thoracic  duct,  receives  all  the  chyliferous  vessels  and 
the  lymphatics  of  the  remaining  part  of  the  body.  It  would 
appear,  from  the  observations  of  the  younger  Lauth,*  that 
there  are  also  other  terminations  of  the  lymphatics  in  the 
veins;  to  wit,  such  as  in  the  yet  capillary  state  end  in  the 
veins  of  the  minute  structure  of  organs,  and  such  as  empty 
into  them  in  the  interior  of  the  lymphatic  glands.  Pre- 
viously to  Lauth,  this  sentiment  of  communication  with 
the  veins  was  strongly  advocated  by  several  anatomists  and 
physiologists,  for  the  following  reasons:  1.  That  the  known 
roots  of  the  lymphatic  system  have  an  area  much  superior 
to  that  of  the  trunks  in  which  they  terminate.  2.  That 
substances  introduced  into  certain  lymphatics  by  absorption 
or  injection,  have  been  found  in  the  contiguous  veins.  3. 
That  a ligature  upon  the  thoracic  duct  only  produced  death 
after  ten  or  fifteen  days,  and  then  the  articles  which  had 
been  absorbed  by  the  intestines,  were  found  in  the  blood. 
4.  And  that  injections  had  proved  this  communication.. 

Notwithstanding  the  well  known  fact  of  injections,  under 
certain  circumstances,  passing  from  the  arteries  into  the 
lymphatics,  anatomists  of  modern  date  have  always  hesitated 
in  admitting  a direct  communication.  M.  Meckel  has  in- 
deed rejected  the  notion  entirely,  on  the  ground  that  the 
fluid  contained  in  the  trunks  of  the  absorbents,  is  always 
the  same  as  one  finds  at  their  commencement.  For  exam- 
ple, the  lymphatics  coming  from  the  liver  contain  a fluid 


Loc.  cit. 


2S4 


CIRCULATORY  SYSTEM. 


like  bile;  those  which  come  from  the  mammae  contain  a 
fluid  like  milk;  those  which  come  from  parts  suffering  from 
an  extravasation  of  blood,  contain  a sanguineous  fluid;  the 
bronchial  glands  are  coloured  by  the  black  pigment  brought 
to  them  from  the  lungs;  poisonous  matter,  as  that  of  the 
smalhpox  or  venereal,  irritates  and  inflames  the  lymphatics 
that  lie  in  the  course  of  its  introduction  into  the  system. 
For  these  reasons  it  would  appear,  that  the  arteries  do  not 
continue  themselves  into  the  lymphatics  as  they  do  into  the 
reins;  yet  the  observations  of  M.  Lauth  seem  to  have 
proved  the  point,  that  some  of  the  lymphatics  take  their 
origin  from  the  internal  surface  of  the  arteries,  and. that  it 
is  probably  through  them  that  injections  have  been  forced 
from  one  system  into  the  other. 

The  coats  of  the  lymphatics  generally  are  too  thin  and 
transparent  for  an  investigation  of  their  structure;  but  as 
those  of  the  thoracic  duct  are  sufficiently  large  for  the  pur- 
pose, one  may  estimate  the  structure  of  other  trunks  by  it. 
It  is  thus  ascertained  that  they  consist  of  two  coats,  an  in- 
ternal and  an  external  one. 

The  external  coat  is  somewhat  irregular  in  its  surface, 
from  its  connexion  with  the  adjacent  cellular  substance;  and 
has  a filamentous  appearance  mor^ deeply,  which  has  been 
considered  as  fibrous,  or  muscular  by.  some  anatomists, 
owing  to  its  contraction  upon  the  application  of  certain  sti- 
mulants. The  internal  membrane  is  extremely  fine  and 
perfectly  transparent,  and  is  remarkable  for  its  frequent  du- 
plications, whereby  a system  of  valves  is  produced  resem- 
bling those  of  the  veins.  These  valves  are  generally  of  a 
semilunar  or  parabolic  shape,  and  are  arranged  in  pairs, 
though  according  to  Lauth,*  some  of  them  are  circular,  and 
do  not  close  the  canal  entirely.  The  pairs  are  not  placed 
at  stated  distances  from  one  another,  but  vary  in  different 
parts  of  the  body;  in  some  places  there  are  several  in  the 
course  of  an  inch,  and  in  others  not  one  pair.  As  a gene- 
ral rule,  they  are  less  frequent  as  the  trunk  increases  in 
magnitude;  hence  the  thoracic  duct  has  but  very  few  of 


Loc.  ell. 


ANATOMY  OP  THE  ABSORBENT  SYSTEM. 


2S5 


them.  The  valves,  by  having  their  semicircumference 
fixed,  while  the  diameter  is  loose  and  inclined  in  the  course 
of  the  circulation,  prevent  the  retrograde  movement  of  the 
contained  fluid.  The  enlargement  of  the  trunk  at  their 
outer  face  into  sinuses  resembling  those  at  the  valves  of  the 
veins,  gives  also  to  the  lymphatic  trunk  the  knotted  condi- 
tion when  it  is  fully  injected. 

The  coats  of  the  lymphatic  vessels,  though  very  thin, 
are  yet  dense  and  extremely  strong,  much  more  in  propor- 
tion than  those  of  any  other  tubes.  They  are  both  exten- 
sible and  elastic,  possess  striking  powers  of  spontaneous  con- 
traction in  the  living  body,  and  also  in  the  dead,  but  to  a 
less  extent.  They  are  furnished  with  arteries  and  veins, 
and  probably  with  nerves  also,  from  their  sensibility  in  a 
state  of  inflammation.  And  as  they  stand  in  need  of  a si- 
milar organization  with  other  canals,  their  parietes  are  said 
also  to  have  lymphatics. 

The  absorbent  vessels  are  by  some  divided  into  lacteals 
and  lymphatics,*  the  first  term  expressing  those  which  con- 
vey the  chyle  from  the  intestines,  and  the  second  such  as 
are  found  in  other  parts  of  the  system.  As  the  difference 
is  more  in  the  fluid  conducted  than  in  the  structure  of  the 
vessels  themselves,  the  division  is  rather  superfluous.  There 
is  also  a distinction  of  the  lymphatics,  arising  from  their 
situation,  as  in  the  veins;  some  of  them  are  called  superfi- 
cial, and  the  others  deep  seated.  The  arrangement  upon 
which  this  nomenclature  depends,  is  found  in  the  head, 
trunk,  extremities,  and  in  the  most  of  the  viscera.  The 
deep  seated  trunks  are  the  largest,  but  the  least  nume- 
rous. 

• This  division  has  been  handed  down  from  the  time  of  Bartholine,  who, 
not  suspecting  the  absorbing  powers  of  the  lymphatics,  held  them  only  as 
organs  of  circulation  for  restoring  to  the  heart  the  serum  of  the  blood.  The 
sagacious  mind  of  the  late  Dr.  W.  Hunter  lii’st  imagined  their  absorbing 
powers,  and  established  the  theory  of  their  identity  of  function,  in  this  re- 
spect, with  the  lacteals.  The  priority  of  the  theory  was  warmly  contested 
for  Dr.  Monroe,  of  Edinburgh. 


CIKCULATORy  SYSTEAI. 


2S6 


Of  the  Lymphatic  Glands. 

The  Lymphatic  or  Absorbent  Glands  or  Ganglions,  some- 
times called  waxen  kernels  in  common  language,  are  an  ap- 
pendage of  a very  important  description  to  the  absorbent 
system.  They  are  flattened  ovoidal  bodies,  of  a reddish  ash 
colour,  indurated  so  as  to  afford  a strong  resistance  to  pres- 
sure, and  of  a variable  volume  from  a line  to  twelve  lines 
in  their  long  diameter.  They  are  found  principally  in  clus- 
ters or  chains,  and  more  abundant  in  the  neck,  in  the  groin, 
in  the  arm-pit,  in  the  mesentery,  and  about  the  bifurcation 
of  the  trachea. 

The  lymphatic  vessels,  in  their  course  towards  the  tho- 
racic duct  have  to  pass  through  one  or  more  of  these  glands. 
This  rule  is  almost  universal;  some  exceptions,  however, 
to  it  in  the  case  of  the  lower  extremity,  have  been  stated 
by  Mr.  Hewson,  and  in  the  case  of  the  back  by  Mr.  Cruik- 
shank;*  the  latter  believes  Mr.  H.  to  have  been  under  some 
misapprehension  in  this  statement  concerning  the  extremi- 
ties, as  it  had  not  been  verified  by  the  result  of  his  own  in- 
vestigations. The  vessels  that  enter  into  the  glands  are 
called  vasa  inferentia,  while  those  that  depart  from  them 
are  the  vasa  eflerentia.  As,  owing,  to  the  juxtaposition  of 
many  of  these  glands,  the  vessels  between  them  are  very 
short,  this  distinction  would  likewise  seem  almost  super- 
fluous, because  one  has  scarcely  space  to  apply  the  term  ef- 
ferentia,  before  the  same  vessels  enter  into  the  consecutive 
gland,  thereby  becoming  inferentia.  For  the  most  part, 
the  vasa  inferentia  are  less  numerous  and  somewhat  larger 
than  the  eflerentia.  The  former,  as  they  leave  the  gland, 
radiate  into  smaller  branches,  while  the  latter  are  formed 
from  the  convergence  of  smaller  branches. 

Each  lymphatic  gland  is  surrounded  by  a capsule,  re- 
sembling condensed  cellular  substance,  which  adheres  very 
closely  to  the  gland,  and  from  which  cause  many  anatomists 
are  disposed  to  deny  its  existence,  at  least  as  a distinct 

• Anat.  of  Absorb.  Vesaels,  second  Edit  p.  79.  London,  1790 


ANATOMY  OF  THE  ABSORBENT  SYSTEM.  287 

membrane.  They  are  also  abundantly  furnished  vvith  ar- 
teries and  with  veins  destitute  of  valves;  but  though  they 
are  penetrated  by  nervous  filaments,  it  is  not  yet  satisfac- 
torily ascertained  that  any  remain  vvith  them;  it  is,  how- 
ever, more  probable  than  otherwise.  Their  connexion  with 
the  surrounding  cellular  substance  is  sufficiently  loose  to 
permit  them,  in  certain  parts,  to  be  slid  moderately  back- 
wards and  forwards.  When  this  motion  is  arrested,  it  is 
from  inflammation  about  them. 

The  capsule  of  the  lymphatic  gland,  like  that  of  other 
glands,  sends  processes  within  to  keep  its  parts  together, 
and  to  conduct  the  blood  vessels.  It  also  contains  a pecu- 
liar fluid  called,  by  Haller,  succus  proprius,  which  is  prin- 
cipally found  in  young  animals,  diminishes  as  they  advance 
in  age,  and  finally  disappears  It  is  of  various  colours,  but 
more  frequently  white;  it  appears  to  have  globular  particles 
in  it,  which  the  late  Mr.  Hewson,  for  divers,  reasons,' 
thought  to  become  afterwards  the  red  globules  of  blood. 

When  a lymphatic  giand  is  injected  with  quicksilver,  it 
appears  to  be  made  up  by  the  minute  branching  of  the  vasa 
inferentia,  and  the  ’ roots  of  the  vasa  efferentia,  the  former 
being  continued  into  the  latter.  There  is  also  some  appear- 
ance of  small  cells  intermediate  to  these  two  orders  of  ves- 
sels. All  anatomists  admit  the  former  opinion,  but  many 
reject  the  latter,  under  a presumption  that  the  appearance  is 
delusive.  The  arguments,  however,  seem  to  be  in  favour  of 
their  existence.  Mr.  Cruikshank,*  whose  address  in  these 
matters  was  certainly  of  the  first  order,  declares  that  he 
never  failed  to  perceive  them,  and  particularly  well,  just 
as  the  mercury  was  entering  the  gland.  This  arrangement 
is  still  more  readily  made  out  in  animals,  as  the  horse,  ass, 
mule.  It  also  seems,  from  his  observations,  that  when  there 
are  more  than  one  vas  inferens  and  eflerens,  there  are  cells 
for  each  set,  which  are  kept  distinct  from  the  cells  of  the 
others,  though  they  communicate  freely  with  their  cognates. 
Mr.  Abernethy’s  investigations  on  the  mesenteric  glands  of 
whales,  coincide  with  the  views  of  Mr.  Cruikshank:  he 


Loc.  cit.  p.  85,  n.  m. 


288 


CIRCULATORY  SYSTEM. 


states,  indeed,  the  cells  as  being  large  spherical  bags,  into 
which  the  lacteals  plainly  open.  The  celebrated  Mascagni 
also  acknowledges,  and,  indeed,  describes  the  cellular  struc- 
ture of  these  glands,*  which  he  had  ascertained  both  by 
quicksilver  and  by  wax  injections.  The  improved  notions 
of  modern  anatomy  upon  what  is  called  the  erectile  tissue, 
that  is,  the  cells  intermediate  to  arteries  and  veins,  as  in  the 
penis  and  other  places,  now  considered  rather  as  the  dilated 
extremities  of  vessels,  would  also  assist  in  warranting  the 
opinion  advocated.  The  celebrated  Ruysch  thought  that  he 
had  discovered  acini  in  the  lymphatic  glands,  and  sent  his 
injected  preparation  illustrative  of  them  to  Boerhaave. 
Some  idea  of  the  enthusiasm  of  the  old  anatomists  may  be 
conceived  by  his  saying,  “quando  jam  clarius  et  perfectius 
videbam  hsec  omnia,  prse  gaudio  exsiliebam.” 


When  the  absorbing  powers  of  the  lymphatics  had  been 
established  by  Dr.  W.  Hunter,  they  were  for  a long  time 
considered  as  the  exclusive  functionaries  in  this  operation; 
and  the  opinions  previously  entertained  had  sunk  into  such 
disrepute  from  some  experiments  of  Mr.  John  Hunter,!  that 
they  were  considered  rather  as  food  for  literary  research  and 
curiosity,  than  for  deliberate  adoption.  In  the  year  1809, 
M Magendie  reported  his  experiments  on  absorption,  which 
seemed  to  favour  the  notion  that  the  veins  also  assisted  in 
this  office,  a theory  as  ancient  as  Galen.  The  more  recent 
observations  of  Fohman,  in  1821,  and  Lauth,  in  1824,  on 
the  communications  of  the  lymphatics  with  the  veins,  in  the 
midst  of  the  tissues  of  organs,  and  in  the  lymphatic  glands, 
seem  now  to  explain  away  again  the  theories  of  the  absorbing 
powers  of  the  veins,  and  to  reinstate  the  lymphatics  in  their 
reputed  exclusive  functions.  It  is  also  stated  that  an  ana- 
tomist of  Florence,  M.  Lippi,  has  still  more  lately  found 
several  large  lymphatic  trunks  entering  into  the  ascending 
cava.  The  connexion  of  the  lymphatic  system  with  the 


* Vasor.  I.ymph.  Hist. 


j Med.  Commentaries. 


ANATOMV  OF  THE  ABSORBENT  SYSTEM. 


289 


vena  cava  ascendens,  and  also  with  the  external  iliac  veins 
has  been  further  demonstrated  by  certain  preparations,  ex- 
hibited by  M.  Amussat  to  the  Academie  Royale.*  M.  Fo- 
dera  has,  however,  again  brought  the  subject  under  discus- 
sion, by  multiplying  the  active  agents  of  this  function,  and 
says,  that  his  experiments  prove  that  all  organized  tissues 
enjoy  it,  and  not  certain  parts  only,  as  has  been  heretofore 
supposed;!  from  which  it  results  that  most  of  the  rules  in 
regard  to  the  application  of  local  remedies  are  inexact,  and 
that  we  should  have  more  regard  to  the  thickness  and  den 
sity  of  tissues,  to  the  quantity  and  rapidity  of  their  circula- 
tion, than  to  simple  locality.! 


CHAPTER  VI. 

OF  THE  SPECIAL  ANATOMY  OF  THE  ABSORBENT  SYSTE5L 
SECT.  I. OF  THE  ABSORBENTS  OF  THE  HEAD  AND  NECK. 

The  Superficial  Absorbents  of  the  head  are  found  in  com- 
pany with  the  several  branches  of  the  temporal,  th*e  occipi- 
tal, the  frontal,  and  the  facial  arteries,  and,  in  order  to  get 
into  the  lymphatic  trunks  leading  to  the  thoracic  duct,  fol- 
low or  rather  reverse  the  course  of  their  respective  arteries. 
There  are  at  least  two  absorbent  trunks  for  one  arterial,  and 
frequently  more:  those  on  the  face  are  more  abundant  than 
such  as  are  on  the  side  of  the  cranium,  owing  to  the  excess 
of  cellular  substance  on  the  former.  The  absorbents  of  these 

* Am.  Med.  Jour.  vol.  i.  p.  422. 

! Recherches  Experimentales  sur  1’ Absorption  et  I’Exhalation.  Paris, 
1824. 

t For  a most  interesting  and  instructive  series  of  experiments  on  the  laws 
and  phenomena  of  absorption,  see  Philadelphia  Journal  of  the  Medical  and 
Physical  Sciences.  Nos.  6 and  10.  The  experiments  were  executed  by 
Messrs,  Lawrence,  Coates,  and  Harlan,  of  this  city. 

VoL.  II.— 37 


CIRCCTLATORl'  SYSTEM. 


290 

two  regions  anastomose  freely  beneath  the  external  ear,  be- 
tween the  skin  and  the  parotid  gland. 

The  Deep-Seated  Absorbents  of  the  head  have  been  fol- 
lowed to  the  membranes  of  the  brain,  but  not  further. 
Rnysch  observed  them  between  the  tunica  arachnoidea  and 
pia  mater,  inflated  with  air,  and  called  them  vasa  pseudo- 
lymphatica.  Lancisius,  Pacchioni,  and  others,  assert  their 
having  found  them  in  the  pia  mater.  Doubts,  however,  are 
cast  upon  these  several  observations,  owing  to  such  vessels 
not  having  been  injected  with  quicksilver,  and  from  the 
want  of  a valvular  appearance  in  them:  also  from  the  want 
of  lymphatic  glands  in  the  brain.  Their  existence,  however, 
would  seem  to  be  sulFiciently  proved,  both  from  general 
analogy,  and  from  affections  of  the  brain  producing  swellings 
in  the  glands  of  the  neck.  On  the  dura  mater  they  have 
been  traced  along  the  course  of  its  arteries.  They  descend 
from  the  interior  of  the  cranium  into  the  neck,  along  the 
carotid  and  vertebral  arteries.  The  absence  of  lymphatic 
glands  in  the  cranium  may  be  accounted  for  from  the  fact, 
that  the  ready  tendency  of  these,  organs  to  swell  upon  slight 
causes  of  irritation,  would  have  rendered  the  individual 
liable  to  death  from  compression  of  the  brain,  by  their  tu- 
mefaction. Mr.  Cruikshank  has  found  lymphatic  glands  in 
the  carotid  canal. 

The  Deep  Lymphatics  of  the  face,  as  those  from  the  in- 
terior of  the  nose,  of  the  orbit,  of  the  tongue  and  mouth, 
attend  the  arteries  which  respectively  supply  those  parts. 

These  several  absorbents,  from  the  surface  and  from  the 
interior  of  the  head,  descend  to  the  base  of  the  cranium,  and 
then  begin  to  pass  through  the  chain  of  lymphatic  glands 
situated  along  the  course  of  the  great  blood  vessels  of  the 
neck.  They  lie,  for  the  most  part,  under  the  sterno-mas- 
toid  muscle,  and,  when  successfully  injected,  are  thought  to 
form  the  most  brilliant  plexus  of  absorbents  in  the  whole 
frame.  On  each  side  of  the  neck,  one  or  more  common 
trunks  are  at  length  formed;  that  on  the  left  side  joins  the 
Left  Thoracic  Duct  near  its  termination,  while  the  one  on 
the  right  assists  in  forming  the  duct,  peculiar  to  that  side, 


ANATOMV  OF  THE  ABSORBENT  SYSTEM.  291 

the  right  Thoracic  Duct,  or  more  properly  called,  Brachio 
Cephalic. 

The  lymphatic  vessels  of  the  muscles  of  the  neck,  and 
those  of  the  thyroid  gland,  enter  into  the  trunks  of  the 
neck.  According  to  Mr.  Cruikshank,  those  of  the  thyroid 
gland  may  be  readily  injected  by  plunging  a lancet  at  ran- 
dom into  its  substance,  and  then  introducing  air  or  quick- 
silver. 

Of  the  Absorbent  Glands  of  the  Head  and  Neck. 

The  only  claim  of  lymphatic  glands  to  an  existence  in 
the  cavity  of  the  cranium,  is  founded  upon  a supposition 
that  the  Pineal,  the  Pituitary,  and  Pacchioni’s  Glands  are 
of  this  character;  but  it  is  far  from  being  established,  and 
there  seems  indeed  to  be  some  doubt  whether  the  glands 
found  in  the  carotid  canal,  by  Mr.  Cruikshank,  are  not  the 
carotid  ganglion  of  the  Sympathetic,  lately  noticed  by  Lau- 
monier. 

On  the  external  surface  of  the  cranium,  over  the  inser- 
tion of  the  sterno-mastoid  muscle,  there  are  from  four  to 
six  of  a small  volume;  on  the  face  there  are  one  or  more 
small  ones,  below  the  zygoma,  and  from  two  to  four  on  the 
external  surface  of  the  parotid;  there  are  one  or  more  small 
ones  situated'  in  the  substance  of  the  parotid  gland,  which, 
according  to  Burns,  are  generally  the  seat  of  tumours  falsely 
attributed  to  the  parotid  itself.  There  are  also  some  small 
glands  along  the  facial  artery  as  it  ascends  from  the  base  of 
the  jaw  to  the  corner  of  the  mouth. 

On  the  neck  there  are  two  or  more  small  glands,  immedi- 
ately under  the  skin  of  the  symphisis  of  the  jaw,  and  eight 
or  nine  around  the  submaxillary  gland.  The  most  nume- 
rous congeries  of  glands  on  the  neck  is,  however,  along  its 
great  blood  vessels,  and  covered  more  or  less  by  the  sterno- 
mastoid  muscle,  being  principally  between  its  posterior 
margin  and  the  anterior  of  the  trapezius.  Along  the  latter 
line  there  are  about  twenty,  in  addition  to  six  just  above 
the  superior  margin  of  the  clavicle.  On  the  trachea,  just 


292 


CIRCULATORY  SYSTEM. 


above  the  sternum,  there  are  four,  forming  the  upper  end 
of  a series  which  descends  along  the  oesophagus  and  trachea 
to  the  root  of  the  lungs. 

SECT.  II. OF  THE  ABSORBENTS  OP  THE  UPPER  EXTREMI- 

TIES, AND  OF  THE  CONTIGUOUS  PARTS  OP  THE  TRUNK  OF 

THE  BODY. 

The  superficial  absorbents  of  the  upper  extremity  are 
very  numerous,  and  lie  between  its  skin  and  aponeurosis. 
They  begin  at  the  ends  of  the  fingers  and  thumb;  there  be- 
ing two  or  more  branches  for  each,  both  before  and  behind. 
The  posterior  branches  pass  to  the  back  of  the  hand  and  of 
the  fore-arm;  some  of  them,  more  especially  those  from 
about  the  thumb,  run  up  along  the  radial  side  of  the  fore- 
arm to  the  bend  of  the  arm;  but  by  far  the  greater  part  of 
them  incline  very  gradually  in  a semi-spiral  manner  to- 
wards the  ulna,  and  then  to  the  front  of  the  fore-arm. 

Such  of  the  superficial  vessels  as  come  from  the  front  of 
the  fingers  and  hand,  continue  to  ascend  straight  up  the  fore- 
arm to  its  bend.  These  vessels  of  the  fore-arm  are  so  nu- 
merous that  for  every  few  lines  there  is  an  ascending  trunk 
on  its  circumference:  some  of  them  coalesce,  others  form 
plexuses,  and  their  number  is  much  reduced  at  the  elbow. 

From  the  elbow  the  superficial  lymphatics  ascend  to  the 
axilla  in  fifteen  or  twenty  parallel  trunks,  along  the  inter- 
nal margin  and  the  front  surface  of  the  biceps  flexor  cubiti. 
The  outer  side  of  the  arm  has  comparatively  but  few  ab- 
sorbent trunks  upon  it,  but  some  few  trunks  follow  the 
course  of  the  cephalic  vein,  penetrate  with  it  into  the  axil- 
la, and  then  join  the  inferior  lymphatics  of  the  neck. 

The  Deep  Absorbents  of  the  upper  extremity  attend  the 
arteries,  and  are  at  least  two  for  each  principal  artery. 
They  anastomose  with  the  superficial  ones  from  time  to 
time,  and  at  last  terminate  in  the  axillary  glands.  As  they 
follow  strictly  the  course  of  the  arteries,  a further  specifi- 
cation is  needless. 


ABSORBENTS  OP  THE  UPPER  EXTREMITIES.  293 

The  Superficial  Absorbents  of  the  contiguous  portions  of 
the  trunk  of  the  body  are  not  by  any  means  so  numerous  as 
those  of  the  upper  extremity;  they  consequently  are  more 
distant  from  one  another,  and  they  also  go  along  in  a more 
serpentine  manner.  From  the  nape  of  the  neck  to  the  low- 
er part  of  the  loins  they  all  converge  to  the  arm-pit.  The 
absorbents  which  are  situated  on  the  front  of  the  pectoralis 
major  muscle,  and  those  on  the  side  of  the  body  from  the 
arm-pit  to  the  hip,  also  converge  to  the  axilla.  In  regard 
to  the  two  latter  places,  however,  some  of  their  absorbents 
by  penetrating  the  parietes  of  the  thorax  or  abdomen,  re- 
spectively join  the  internal  absorbent  trunks  of  these  ca- 
vities. 

These  several  lymphatics  from  the  upper  extremity  and 
from  the  trunk,  traverse  the  axillary  glands,  and  are  suc- 
cessively reduced  in  number  to  four  or  five  voluminous 
trunks,  which  surround  the  subclavian  artery.  While  in 
the  axilla  they  are  re-enforced  by  the  deep  lymphatics  from 
beneath  the  pectoralis  major,  the  latissimus  dorsi,  and  the 
shoulder.  Their  number  being  again  reduced,  they  go 
along  the  subclavian  vein  over  the  first  rib;  those  of  the 
left  side  open  either  into  the  thoracic  duct  at  its  termina- 
tion, or  into  the  subclavian  vein  near  it;  but  those  on  the 
right  are  finally  assembled  into  the  single  large  trunk,  bra- 
chio  cephalic,  which  discharges  into  the  angle  of  junction 
of  the  right  internal  jugular  and  subclavian  vein. 

Msorbent  Glands  of  the  Upper  Extremity. 

These  glands  are  rarely  found  on  the  fore-arm,  but  when 
they  do  exist,  it  is  in  the  course  of  the  deep  absorbents,  and 
they  are  very  small,  and  but  few.  From  one  to  four  are 
found  scattered  on  the  front  of  the  elbow  and  internal  con- 
dyle. From  four  to  seven  exist  along  the  sheath  of  the  hu- 
meral vessels  and  nerves. 

The  axillary  glands  are  very  numerous,  and  of  diflferent 
sizes;  they  are  dispersed  throughout  the  cellular  substance 
of  the  axilla,  reposing  on  the  serratus  major  anticus,  be- 


294 


CIRCULATORY  SYSTEM. 


tween  the  pectoral  muscles  and  those  of  the  shoulder,  and 
being  for  the  most  part  below  the  axillary  vessels  and 
nei’ves,  but  some  reposing  immediately  upon  them,  and 
forming  a chain  from  the  lower  part  of  the  axilla  to  the 
clavicle.  Their  number  is  from  fifteen  to  thirty-five  or 
forty.  All  the  absorbents  which  observe  the  rout  of  the 
axilla  to  reach  the  thoracic  duct  have  to  pass  through  these 
glands. 

SECT.  III. ABSORBENTS  OP  THE  INFERIOR  EXTREMITIES, 

AND  OF  THE  CONTIGUOUS  PARTS  OP  THE  TRUNK  OP  THE 

BODY. 

The  superficial  absorbents,  like  those  of  the  upper  extre- 
mity, are  placed  between  the  skin  and  the  aponeurosis,  in 
the  cellular  tissue  that  contains  the  subcutaneous  veins. 
They  are  also  very  abundant,  and  are  found  every  few  lines 
on  the  circumference  of  the  limb;  they  are,  however,  more 
numerous  internally,  than  externally,  and  for  the  most  part 
run  upwards. 

Those  on  the  inner  or  anterior  side  of  the  limb,  are  first 
perceived  on  the  back  of  the  toes  and  foot.  They  incline 
over  the  front  of  the  ankle,  and  its  internal  face  to  the  in- 
ner side  of  the  leg;  they  then  ascend  over  the  inner  side  of 
the  knee,  and  along  the  same  side  of  the  thigh  to  the  groin. 
The  superficial  absorbents  of  the  back  of  the  lower  extremity 
are  first  perceived  on  the  sole  of  the  foot.  They  ascend 
along  the  back  of  the  outer  ankle  and  of  the  leg  above  the 
knee;  they  then  incline  semispirally  inwards,  so  as  to 
bring  themselves  to  the  front  of  the  thigh.  These  several 
absorbents,  though  there  are  but  few  on  the  foot,  augment 
continually  in  number  by  new  accessions  in  their  ascent. 
All  those  on  the  posterior  internal  face  of  the  thigh  wind 
over  its  internal  side,  while  such  as  are  on  its  posterior 
external  face  wind  over  the  outer  side,  to  reach  the  ingui- 
nal glands. 

The  Deep  Absorbents  adhere  to  the  arteries,  being  at  least 


ABSORBENTS  OF  THE  INFERIOR  EXTREMITIES.  295 

two  to  each,  and  adopting  the  same  distribution  and  nomen- 
clature. The  anterior  tibial  begins  in  the  sole  of  the  foot, 
and  arises  to  its  back  between  the  two  first  metatarsal  bones; 
another  branch  begins  on  the  dorsum  of  the  foot.  The  first 
pursues  the  course  of  the  anterior  tibial  artery  through  the 
interosseal  ligament  to  the  ham;  the  second  frequently  joins 
the  peroneal  absorbents  about  half  way  up  the  leg.  The  pos- 
terior tibial  and  the  peroneal  absorbents,  as  they  cruise  along 
their  respective  arteries,  do  not  require  any  further  com- 
ment. There  is  a fourth  set  of  these  deep  absorbents,  amount- 
ing to  two  or  three  in  number,  which  attend  the  external 
saphena  vein,  and  come  from  the  external  side  of  the  foot. 
Getting  between  the  heads  of  the  gastrocnemii  muscles, 
they  are  re-enforced  by  other  trunks  from  this  muscle; 
some  of  the  branches  then  associate  themselves  with  the  su- 
perficial lymphatics,  and  others  penetrate  the  ham  so  as  to 
join  the  deep  trunks  thei'e. 

The  deep  absorbents  of  the  leg  coalesce  partially  in  the 
ham  and  ascend  along  the  popliteal  artery.  On  the  thigh, 
there  are  from  four  to  eight  of  these  trunks  attending  the 
femoral  artery,  and  receiving  additions  as  the  latter  detaches 
branches. 

There  are  two  or  three  lymphatic  vessels  on  each  side  of 
the  penis,  which  begin  at  its  glans  and  prepuce,  and  ti'a- 
versing  the  length  of  this  organ,  wind  above  the  external 
abdominal  ring  to  join  the  nearest  inguinal  gland.  There  are 
several  from  the  side  of  the  scrotum  and  perineum,  which 
ascend  along  the  chord  and  thigh  to  join  also  the  nearest 
inguinal  gland.  In  the  female,  those  of  the  labia  externa  and 
clitoris  correspond  with  those  of  the  scrotum  and  penis. 

The  superficial  absorbent  trunks,  from  the  lower  front  of 
the  abdomen,  are  not  numerous;  they  descend  and  converge 
also  to  the  inguinal  glands.  Some  of  those  from  the  loins, 
such  as  do  not  ascend  to  the  axilla,  advance  to  the  inguinal 
glands.  Those  of  the  buttocks  do  the  same. 


29G 


CIRCULATORY  SYSTEM. 


Absorbent  Glands  of  the  Lower  Extremity. 

Absorbent  Glands,  below  the  knee,  are  not  abundant,  or 
indeed  very  common;  yet  one  or  two  exist  sometimes  in  the 
course  of  the  anterior  tibial  artery  in  the  upper  part  of  the 
leg.  The  popliteal  glands  are  three  or  four;  they  are  small 
and  scattered  at  wide  intervals  in  the  fat  of  the  ham  around 
its  vessels.  From  the  latter  to  the  groin,  they  are  not 
usually  found  at  all. 

The  Inguinal  Glands  are  amongst  the  largest  in  the  sys- 
tem; they  repose  along  the  anterior  margin  of  Poupart’s 
ligament  and  a little  below,  and  are  readily  felt  beneath  the- 
skin.  The  superficial  vary  in  number,  in  different  indivi- 
duals, from  seven  to  twenty,  being  more  numerous  as  they 
are  smaller,  and  are  placed  between  the  laminae  of  the  fascia 
superficialis.  They  receive,  first  of  all,  the  superficial  lym- 
phatics of  all  the  parts  mentioned.  The  deep-seated  are 
smaller,  are  a little  lower  down  on  the  thigh,  and  lay  along 
the  course  of  the  femoral  artery,  beneath  the  aponeurosis  of 
the  thigh;  they  are  from  three  to  seven  in  number,  but  are 
much  less  constant  than  the  superficial. 

SECT.  IV. DEEP  ABSORBENTS  OF  THE  PELVIS. 

The  Deep  Absorbents  of  the  parietes  of  the  pelvis,  as  in 
other  cases,  attend  the  arteries  of  the  part  and  have  the  same 
names.  The  obturators  come  from  the  heads  of  the  adductor 
muscles,  and,  passing  through  the  obturator  foramen,  end  in 
the  hypogastric  glands.  The  ischiatics  come  from  the  small 
muscles  on  the  back  of  the  hip  joint,  and  getting  into  the 
pelvis  along  with  the  sciatic  artery,  they  also  terminate  in 
the  hypogastric  glands.  The  gluteals  come  from  the  three 
gluteal  muscles,  and  entering  the  pelvis  along  with  the  ar- 
tery at  the  superior  margin  of  the  sciatic  notch,  they  like- 
wise terminate  in  the  hypogastric  glands  along  with  some 
vessels  from  the  anus  and  the  perineum.  The  ilio-lumbar, 
the  sacral,  and  the  circumflex  iliac  absorbents,  also  follow 
their  respective  arteries  and  terminate  in  the  nearest  glands. 


deep  absorbents  op  the  pelvis. 


297 


The  absorbents  of  the  Testicle  are  numerous  and  large; 
according  to  Dr.  W.  Hunter,*  they  can  sometimes  be  very 
completely  injected  by  a pipe  thrust  into  the  substance  of 
the  testicle,  and  according  to  Cruikshank,  very  advantage- 
ously from  the  vas  deferens. t They  form  two  layers,  one 
superficial  coming  from  the  tunica  vaginalis  testis,  and  the 
other  from  the  substance  of  the  gland.  They  finally  unite 
into  some  six  or  eight  trunks,!  which  ascend  with  the  chord 
through  the  abdominal  canal.  Occasionally  one  or  more  of 
them  is  as  large  as  a crow-quill.  By  following  the  course 
of  the  spermatic  artery,  they  at  last  terminate  in  the  lumbar 
glands. 

The  deep  absorbents  of  the  Penis  accompany  the  arteries, 
and  therefore  either  get  into  the  pelvis  beneath  the  sym- 
phisis of  the  pubes,  or  along  the  crura  and  the  tuberosities 
of  the  ischia;  hence  a chancre  on  the  prepuce  causes  bubo, 
while  one  on  the  glans  very  rarely  does,  and  yet  the  con- 
stitution will  be  equally  affected.  § These  absorbents  ter- 
minate in  the  hypogastric  glands. 

The  deep  absorbents  of  the  Clitoris  follow,  in  the  same 
way,  the  internal  pudic  artery. 

The  absorbents  of  the  Urinary  Bladder  are  also  numerous, 
and  pass  in  several  trunks  from  its  sides  to  the  hypogastric 
glands.  Those  of  the  prostate  gland  and  vesiculae  seminales 
are  associated  with  them. 

The  absorbents  of  the  lower  part  of  the  vagina  accompany 
the  round  ligament  of  the  uterus  through  the  abdominal  ca- 
nal, and  finally  anastomose  with  those  of  the  uterus.  Those 
of  the  upper  portion  of  the  vagina  are  immediately  associ- 
ated with  such  as  belong  to  the  uterus. 

The  absorbents  of  the  uterus  are  not  so  well  seen  in  the 
unimpregnated  state,  but  in  impregnation  they  are  so  pro- 
digiously numerous,  that  when  injected  with  quicksilver, 
one  is  almost  tempted  to  suppose  that  the  uterus  consists 
entirely  in  them.  Mascagni’s  plate  on  this  subject  is  an  ex- 

* Loc.  cit. 
t Mascagni,  loc.  cit. 

VoL.  II. — 38 


f Loc.  cit.  p.  155. 

§ Cruikshank,  loc.  cit. 


298 


CIRCULATORY  SYSTEM. 


quisite  specimen.*  As  they  all  terminate  in  the  hypogastric 
trunks,  the  latter  are  in  such  case  as  large  as  goose  quills. t 

The  hypogastric  plexus,  from  these  several  accessions 
from  the  parietes  and  viscera  of  the  pelvis,  becomes  very 
numerous,  and  follows  the  course  of  the  hypogastric  artery 
in  ascending  into  the  loins. 

There  are  likewise  some  spermatic  absorbents  in  the  fe- 
male, called  so  from  attending  the  vessels  of  the  same  name. 
They  come  from  the  ovarium,  the  Fallopian  tube,  and  the 
round  ligament,  to  terminate  in  the  lumbar  glands;  they 
anastomose  below  with  those  of  the  uterus. 

Of  the  Glands  of  the  Pelvis. 

Some  few  glands  lie  beneath  the  gluteus  maximus  muscle, 
but  the  majority  are  within  the  pelvis.  Those  which  are 
called  the  External  Iliac  are  at  least  six,  frequently  more, 
and  extend  from  Poupart’s  Ligament  to  the  lower  part  of 
the  loins,  being  planted  along  the  external  iliac  artery, 
both  above  and  below.  The  Hypogastric  or  Internal  Iliac 
Glands  are  rather  more  numerous  than  the  others,  and  form 
a chain  along  the  hypogastric  artery.  The  iatter  are  much 
disposed  to  form  large  indurated  masses  from  diseases  of  the 
rectum,  uterus,  and  bladder.  J 

SECT.  V. ABSORBENTS  OF  THE  ORGANS  OF  DIGESTION. 

The  Absorbents  of  the  Stomach  are  very  numerous,  and 
lie  in  two  planes;  one  is  superficial,  being  immediately  be- 
neath the  peritoneal  coat,  and  the  other  is  pi’ofound,  being 
placed  between  the  muscular  and  the  mucous  coat.  They 
are  finally  assembled  into  three  divisions,  which  follow  the 
course  of  the  principal  blood  vessels  of  this  organ. 

One  division,  coming  from  the  anterior  and  the  posterior 
faces  of  the  stomach,  converges  to  its  lesser  curvature,  and 
passes  through  some  six  or  eight  small  glands  in  the  adja- 
cent portion  of  the  lesser  omentum.  Inclining  to  the  right 
of  the  cardiac  orifice,  they  then  pass  , through  some  glands 

* Loc.  cit,  f Cruikshank,  loc.  cit.  + Cruikshank,  loc.  cit. 


ABSORBENTS  OF  THE  ORGANS  OP  DIGESTION.  299 

commoD  to  them  and  to  the  deep  lymphatics  of  the  liver. 
Thdr  numbers  being  reduced,  they  then  descend  behind 
the  pancreas,  and  terminate  in  the  thoracic  duct  near  the 
coeliac  artery.  • 

The  second  division  comes  from  the  left  inferior  portion 
of  the  stomach  and  from  its  greater  extremity,  and  blending 
with  the  absorbents  of  the  spleen  and  pancreas,  goes  with 
them  into  the  thoracic  duct. 

The  third  division  comes  from  the  right  inferior  portion 
of  the  stomach,  and  assembling  towards  the  pylorus,  are  sub- 
sequently mixed  with  some  of  the  absorbents  of  the  liver  and 
of  the  small  intestines,  and  go  along  with  them  into  the  tho- 
racic duct. 

The  absorbents  of  the  Great  Omentum  join  those  of  the 
stomach  and  of  the  colon  at  the  points  most  convenient  to 
them. 

The  absorbents  of  the  Small  Intestines,  like  those  of  the 
stomach,  are  both  superficial  and  deep,  and  from  the  func- 
tion of  conveying  chyle,  have  been  called  lacteals  or  chyli- 
ferous  vessels.  As  the  chyle,  however,  can  only  be  absorbed 
by  the  deep  ones;  and  as  they  and  the  superficial  have  com- 
mon trunks;  as  they  also  absorb,  from  the  intestines,  fluids 
not  converted  into  chyle,  there  seems  to'be  no  necessity  for 
distinguishing  them  by  a particular  epithet.  The  deep  are 
in  the  cellular  coat  of  the  intestine,  and  follow  the  ramifica- 
tions of  the  arteries,  being  double  their  number.  #'he  super- 
ficial being  immediately  beneath  the  peritoneal  coat,  run  for 
some  distance  longitudinally  on  the  gut,  and  then  turn  oft’ 
to  the  mesentery  at  right  angles. 

On  the  mesentery  these  absorbents  are  not  rigidly  bound 
to  the  course  of  the  blood  vessels;  they  converge  in  a slightly 
tortuous  manner  from  its  circumference  to  its  root.  They 
anastomose  with  one  another,  by  which  their  number  is  re- 
duced; and  they  also  have  to  pass  tlirough  the  series  of  me- 
senteric glands.  Tlie  lacteals  of  the  duodenum,  and  jejunum 
are  larger  and  more  numerous  than  those  of  the  ilium,  in  the 
proportion  of  the  greater  extent  of  the  internal  surface  of  the 


i 


300  CIRCULATORY  SYSTEM. 

former  intestines,  from  the  number  of  their  valvulae  conni- 
ventes.  The  vessels  of  the  mesentery,  after  having  cleared 
the  series  of  glands,  and  held  some  intercourse  with  the 
lymjfliatics  of  the  spleen,  liver,  stomach,* and  pancreas,  are 
reduced  at  last  into  one  or  more  large  trunks,  which,  observ- 
ing the  course  of  the  superior  mesenteric  artery,  empty 
near  the  root  of  the  latter,  but  sometimes  lower  down,  into 
the  thoracic  duct. 

The  Absorbents  of  the  Large  Intestines  are  much  less  nu- 
merous than  those  of  the  small.  They  are  also  superficial 
and  deep,  and  observe  the  course  of  the  blood  vessels.  Those 
from  the  right  portion  and  middle  of  the  colon  join  the  lacteals 
of  the  mesentei'y,  while  such  as  belong  to  the  sigmoid  flex- 
ure follow  the  inferior  mesenteric  artery  up  to  the  lumbar 
glands.  Those  of  the  rectum  go  partly  into  the  lumbar 
and  partly  into  the  hypogastric  glands,  and  as  its  blood 
vessels  are  more  numerous  than  those  of  other  portions  of 
the  large  intestines,,  its  absorbents  are  in  the  same  propor- 
tion.* . 

The  Absorbents  of  the  Liver  are  exceedingly  numerous, 
and  are  also  injected  with  unusual  ease  from  the  larger  into 
the  smaller  trunks,  from  the  imperfection  of  the  valvular 
arrangements.  They  are  also  superficial  and  deep. 

The  Superficial  Absorbents  of  the  upper  surface  of  the 
liver  run  in  several  divisions,  the  number  of  which  is  un- 
settled. Those  near  the  middle  front  of  the  liver  assemble 
into  six  o^  more  trunks,  which  ascend  the  suspensory  liga- 
ment, and  enter  the  thorax  between  the  diaphragm  and  the 
sternum.  They  are  joined  by  several  trunks  from  the  dia- 
phragm, and  continuing  to  ascend  up  the  anterior  mediasti- 
num between  its  laminae  behind  the  sternum,  they  are  re- 
enforced by  contributions  from  the  pericardium,  from  the 
thymus  gland,  and  from  the  anterior  parietes  of  the  thorax. 
The  division  then  crosses  the  upper  end  of  the  descending 
eava,  and  those  from  the  two  sides  assembling,  they  go  in 
one  or  more  large  trunks  along  the  vena  innominata,  and 
finally  empty  into  the  left  thoracic  duct  near  its  termination. 

* Cruikshank,  loc.  cit. 


ABSORBENTS  OP  THE  ORGANS  OP  DIGESTION.  301 

Sometimes  they  enter  into  the  right  thoracic  duct  It  oc- 
casionally happens  that  a detachment  of  this  division  instead 
of  ascending  through  the  mediastinum  is  directed  towards 
the  coronary  ligament  of  the  liver,  and  being  there  joined 
by  other  vessels,  it  enters  immediately  into  the  thoracic  duct 
at  the  upper  part  of  the  abdominal  cavity,  or  at  the  lower 
of  the  thorax. 

Another  division  comes  from  the  upper  surface  of  the  right 
lobe,  and  gaining  the  right  lateral  ligament,  penetrates  into 
the  thorax  through  the  diaphragm,  and  advancing  along  the 
costal  margin  of  this  muscle,  terminates  in  the  first  division 
under  the  sternum.  Sometimes  one  of  its  branches,  thrice  as 
large  as  a crow  quill,  runs  backward  to  the  spine,  and  is  in- 
serted into  the  thoracic  duct  behind  the  oesophagus,  without 
passing  through  any  gland;  there  are  also,  occasionally,  se- 
veral other  arrangements,  of  the  trunks  of  this  division.* 
Another  division  comes  from  the  upper  surface  of  the  left 
lobe  of  the  liver,  and  its  trunks  advancing  to  the  left  lateral 
ligament,  get  into  the  thorax  through  the  diaphragm.  Some 
of  the  trunks  then  run  forward  on  the  convexity  of  this  mus- 
cle, to  terminate  in  the  trunks  under  the  sternum,  while 
others  retire  backward  to  end  in  the  glands  around  the  oeso- 
phagus immediately  above  the  diaphragm.  * 

There  are  various  departures  from  this  general  arrange- 
ment of  the  absorbents  on  the  upper  surface  of  the  liver;  as 
their  trunks  invariably  reach  the  thoracic  duct  ultimately, 
the  particular  routes  do  not  seem  to  be  rigidly  fixed. 

The  superficial  absorbents  of  the  under  surface  of  the  liver 
present  also,  diversities,  but  they  are  seldom  arranged  into 
so  many  divisions  as  those  of  the  upper  surface.  They  com- 
municate freely  with  the  latter,  and  also  with  the  profound, 
and  finally  assembling  in  the  transverse  fissure,  they  descend 
along  the  capsule  of  Glisson  to  join  and  anastomose  with  the 
contiguous  trunks  from  the  alimentary  canal,  from  the  pan- 
creas and  the  spleen. 

The  Deep  Absorbents  of  the  liver  follow  the  branching  of 
the  vena  portarum,  and  emerging  at  the  transverse  fissure 
pass  through  the  glands  in  the  capsule  of  Glisson,  associ- 


Cruikshank,  loc.  cit. 


302 


CIRCULATORY  SYSTEM. 


ating  themselves  at  the  same  time  with  the  superficial  trunks, 
and  having  a common  termination  with  them.  By  putting 
a ligature  around  the  vena  portarum  of  a living  animal  many 
of  them  are  included  in  it,  they  then  become  exceedingly 
turgid,  and  are  seen  to  diverge  through  the  liver  like  the 
pori  hiliarii. 

The  liver  is  said  to  be  more  abundantly  furnished  with  ab- 
sorbents than  any  other  viscus. 

The  Absorbents  of  the  Spleen  are  also  superficial  and 
deep  seated.  The  former  are  between  the  peritoneal  and  the 
proper  coat,  and  are  injected  with  some  difficulty  in  the  hu- 
man subject,  but  are  very  demonstrable  and  numerous  in 
the  calf.  The  latter  emerge  at  the  fissure  of  the  spleen,  and 
traversing  the  glands  that  lie  along  the  course  of  the  splenic 
artery,  receive  successively  the  absorbents  from  the  pancreas. 
They  finally  end  in  the  thoracic  duct,  after  reciprocal  junc- 
tions and  anastomose  with  the  vessels  from  the  stomach 
and  liver. 

The  Absorbents  of  the  Pancreas  are  also  numerous,  and 
may  be  injected  contrary  to  their  circulation  from  those  of 
the  liver.  They  arise  from  the  substance  of  the  pancreas 
like  its  vessels  by  short  trunks,  which  join  those  of  the 
Splenic  Plexus  at  right  angles. 

The  Absorbents  of  the  Kidneys  are  superficial  and  deep; 
the  former,  though  numerous,  are  too  small  in  the  healthy 
state  of  these  organs  to  be  well  seen,  but  they  become  very 
distinct  from  disease,  and  converge  from  its  periphery  to 
its  fissure.  The  deep  absorbents  accompany  the  vessels, 
and  emerging  with  them  at  the  fissure  are  joined  with  the 
superficial;  they  all  then  run  along  the  emulgent  vessels, 
and  have  frequent  anastomoses  with  those  of  the  testicles  or 
ovaries,  and  with  those  of  the  capsulae  renales.  These  ab- 
sorbents may  be  filled  by  putting  a pipe  into  the  excretory 
duct  of  the  kidney. 

The  Absorbents  of  the  Capsulae  Renales  unite  to  those 
from  the  kidneys,  and,  therefore,  terminate  with  them  in 
the  lumbar  glands. 


ABSORBKNTS  OF  THE  ORGANS  OF  DIGESTION. 


303 


Of  the  Absorbent  Glands  of  the  Abdomen. 

The  cavity  of  the  abdomen  contains  many  more  glands 
than  any  other  region  of  the  body,  both  on  account  of  the 
very  great  extension  of  the  serous  system  in  it,  of  the  func- 
tions exercised  by  its  viscera,  and  of  its  being  traversed  by 
the  absorbents  of  the  lower  extremities.  Many  of  these 
bodies  have  already  been  described  under  the  denomination 
of  hypogastric,  and  external  iliac;  in  addition  to  which 
there  are  a few  between  the  laminaj  of  the  mesorectum  in 
front  of  the  sacrum. 

The  Mesenteric  Glands  are  exceedingly  numerous,  and 
amount  to  between  one  and  two  hundred:  they  begin  at  an 
inch  or  two  from  the  small  intestines,  and  may  be  traced  to 
the  root  of  the  mesentery,  being  placed  between  its  layers 
on  the  convex  side  of  the  upper  mesenteric  artery.  As  the 
intestinal  canal  is  longer  in  some  individuals  than  in  others, 
they  are  proportionately  more  numerous.  Their  largest 
size  seldom  exceeds  that  of  an  almond;  those  belonging  to 
the  jejunum  are  rather  more  developed  than  such  as  belong 
to  the  ileum,  and  they  all  augment  in  size  as  they  approach 
the  root  of  the  mesentery. 

The  Glands  of  the  Mesocolon  are  placed  between  the  la- 
minse  of  this  membrane,  near  the  intestine;  they  receive 
the  absorbents  from  the  large  intestines,  are  much  smaller 
than  those  of  the  mesentery,  and  their  number  seldom  ex- 
ceeds fifty.  Some  few  of  them  are  situated  near  the  root 
of  the  mesocolon.  They  are  by  no  means  so  disposed  to 
tumefaction  from  scrofulus  affections  as  those  of  the  Me- 
sentery. It  is  stated  by  Winslow  that  he  demonstrated  to 
the  Academy  of  Sciences  at  Paris,  chyle  in  the  absorbents 
of  the  Mesocolon;  this  fact  will  assist  us  in  accounting:  for 
the  effects  of  nutritive  glysters. 

The  Gastro-Epiploic  Glands,  are  situated  between  the  la- 
minae of  the  omenta,  where  they  join  the  curvatures  of  the 


304 


CIRCULATORY  SYSTEM. 


stomach.  Their  number  seldom  exceeds  four  or  five  for 
each  curvature,  and  they  receive  the  lymphatics  of  the  sto- 
mach and  omenta. 

The  Caeliac  Glands  are  those  which  belong  to  the  liver, 
the  spleen,  and  the  pancreas:  they  follow  the  course  of  the 
blood  vessels  of  these  organs,  and  are  traversed  by  their 
absorbents.  The  trunk  of  the  vena  portarum  is  surrounded 
by  them,  and  Mr.  Cruikshank  says,  that  he  has  seen  the 
biliary  and  pancreatic  ducts  in  a state  of  compression  from 
their  tumefaction. 

The  Lumbar  Glands  are  very  numerous  and  large;  they 
are  scattered  over  the  whole  region  from  the  base  of  the 
sacrum  to  the  pillars  of  the  diaphragm,  lying  on  each  side 
of  the  bodies  of  the  lumbar  vertebrae,  and  in  front  of  the 
abdominal  aorta  and  vena  cava,  being  concealed  by  the  root 
of  the  mesentery  and  of  the  mesocolon.  They  may  be 
considered  as  continuations  of  all  the  preceding  congeries 
of  glands  in  the  abdomen,  and,  therefore,  when  they,  along 
with  the  vessels  leading  to  them,  are  successfully  injected, 
they  form  so  thick  a plexus  of  absorbents,  reaching  from 
the  pelvis  to  the  concavity  of  the  diaphragm,  that  the  great 
blood  vessels  can  scarcely  be  seen  for  them.  Many  of  the 
vessels  reaching  from  one  to  another,  are  as  large  as  a crow 
quill. 

SECT.  VI. ABSORBENTS  OP  THE  VISCERA  OP  THE  THORAX. 

The  Absorbents  of  the  Lungs  are  thought  to  be  next  in 
abundance  after  those  of  the  liver^  and  are  likewise  divided 
into  two  sets,  the  superficial  and  the  deep  seated.  The 
former  are  beneath  the  pleura  pulmonalis.  Mr.  Cruik- 
shank* says',  that  they  are  not  always  to  be  found,  though 
commonly  he  has  readily  shown  them  covering  with  their 
meshes  the  whole  external  surface  of  the  lung.  The  larger 
meshes  follow  the  interstices  of  the  lobules,  and  within 


**  Loc-  cit.  p.  194. 


ABSORBENTS  OF  THE  VISCERA  OF  THE  THORAX.  305 

them  are  others  of  extreme  delicacy.  The  same  author 
states  that  one  of  the  easiest  methods  of  finding  them,  is  to 
inflate  the  lungs  of  a still-born  child,  from  the  trachea,  and 
the  air  passing  from  its  proper  cells,  will  get  into  the  ab- 
sorbents; a puncture  being  then  made  into  one  of  the  latter, 
quicksilver  may  be  very  readily  introduced.  Some  of  their 
trunks  penetrate  to  the  bottom  of  the  fissures  of  the  lungs, 
and  pass  through  the  glands  there,  while  others  continue 
more  superficial  along  the  internal  face  of  the  lung,  and  so 
reach  the  bronchial  glands. 

The  deep  absorbents  of  the  lungs  observe  the  course  of 
the  pulmonary  vessels  and  of  the  bronchiae.  They  arise 
from  the  substance  of  the  lung,  anastomose  very  freely 
with  the  superficial  vessels,  and,  in  parting  from  the  lung, 
pass  through  the  bronchial  glands,  where  they  are  joined 
by  the  superficial. 

By  the  junction  of  the  branches  from  the  left  lung,  three 
considerable  trunks  are  formed;  one,  which  is  sometimes 
the  size  of  a goose  quill,  is  insei'ted  into  the  thoracic  duct, 
immediately  behind  the  bifurcation  of  the  trachea;  another 
ascends  between  the  trachea  and  the  oesophagus,  to  join  the 
thoracic  duct  near  its  termination;  and  the  third  joins  the 
glands  belonging  to  the  absorbents  of  the  heart.* 

The  absorbents  of  the  right  lung  also  coalesce  into  three 
principal  trunks  at  the  root  of  the  lung,  one  of  them  as- 
cends across  the  front  of  the  superior  cava,  making  in  its 
course,  many  elegant  convolutions,  and  at  length  terminates 
in  the  second  trunk  on  the  left  side.t  The  other  trunks, 
ascending  on  the  side  of  the  trachea  and  having  traversed 
their  glands,  discharge  into  the  right  thoracic  or  brachio- 
cephalic trunk,  or  else  near  it  into  the  right  internal  jugu- 
lar, or  into  the  right  subclavian  vein.  There  are,  in  these 
respects,  diversities  in  difierent  subjects. 

The  trunks  of  the  Absorbents  of  the  Heart  follow  the 
course  of  the  coronary  vessels,  and  distribute  themselves  by 
branches  over  its  whole  surface.  They  are,  without  prc- 

* Cruikshank,  loc.  cit. 

VoL.  II. — 39 


f Cruikshank,  loc.  cit. 


30G 


CIKCULATOKY  SYSTEM. 


vious  management,  easily  discovered;  but  if  the  heart  be 
macerated  in  water  for  several  days,  so  as  to  become  some- 
what putrid,  the  absorbents  are  filled  and  distended  by  the 
gazeous  exhalation:  on  the  puncture  of  one  of  these  vessels 
and  the  introduction  of  a pipe,  they  may  all  be  readily 
filled. 

There  are  three  principal  trunks  of  these  absorbents;  one 
follows  the  right  coronary  artery  to  the  root  of  the  aorta, 
and  then  ascends  over  the  front  surface  of  the  latter  to  the 
top  of  its  arch,  where  it  enters  a gland.  The  other  two 
trunks  follow  the  two  principal  branches  of  the  left  coronary 
artery,  and,  coalescing  near  its  origin,  they  ascend  to  the 
bifurcation  of  the  pulmonary  artery,  and  from  that  along  the 
posterior  face  of  the  arch  of  the  aorta,  to  enter  a gland  be- 
tween it  and  the  trachea.  These  several  vessels  subsequently 
traverse  the  lymphatic  glands  about  the  trachea,  common  to 
the  heart  and  to  the  lungs;  and  ultimately  terminate  under 
varied  circumstances,  either  directly  or  indirectly,  in  the 
left  thoracic  duct,  the  left  internal  jugular,  or  the  subclavian 
vein.  Mr.  Cruikshank  says  that  the  right  coronary  trunk 
empties  into  the  lymphatic  trunks  of  the  right  side  of  the 
neck,  which  shows  that  there  is  no  fixed  arrangement. 

The  Absorbents  of  the  Pericardium  may  also  be  found; 
they  terminate,  like  the  others  of  the  heart,  in  the  bronchial 
glands,  and  are  particularly  associated  with  those  of  the 
thymus  gland. 

The  Absorbents  of  the  (Esophagus  are  so  numerous  as  to 
form  a plexus  from  one  end  to  the  other  of  it.  They  run 
into  the  bronchial  glands,  and  therefore  have  a common  ter- 
mination with  the  absorbents  of  the  heart  and  lungs.  Mr. 
Cruikshank  says,  that  he  has  reason  to  believe  that  he  has 
seen  life  sustained  through  them  alone  and  the  absorbents  of 
the  mouth,  in  a case  where  stricture  prevailed  for  some 
months  just  above  the  cardia,  and  where  the  food,  after  re- 
maining for  three  or  five  minutes  in  the  oesophagus,  wa.«? 
vomited  up.* 


A case  somewhat  similar  has  occurred  in  the  practice  of  Dr.  Physick. 


ABSORBENTS  OF  THE  PARIETES  OF  THE  TRUNK.  307 

The  Absorbents  of  the  Thymus  Gland  are  very  abundant 
in  the  infant,  but  diminish  with  the  rest  of  the  structure  in 
the  adult:  they  terminate  in  the  bronchial  glands  also. 

SECT.  VII. THE  ABSORBENTS  OP  THE  PARIETES  OF  THE 

TRUNK. 

In  addition  to  the  absorbents  mentioned  as  belonging  to 
the  internal  and  external  parietes  of  the  pelvis,  there  are 
some  others  belonging  to  this  cavity,  as  the  ilio  lumbar,  the 
sacral,  and  the  circumflex. 

The  Ilio  Lumbar  Lymphatics  come  from  the  parts  to 
which  the  artery  of  the  same  name  is  distributed,  and,  as- 
sembling into  two  or  more  large  trunks  which  pass  beneath 
the  psoas  magnus  muscle,  one  of  them  joins  the  lumbar 
glands,  and  another  the  hypogastric. 

The  Sacral  Lymphatics  arise  from  the  cellular  tissue  in 
front  of  the  sacrum  and  from  the  spinal  canal  in  the  latter. 
Emerging  through  its  foramina  in  front,  they  terminate  in 
the  lower  part  of  the  lumbar  and  in  the  hypogastric  plexus. 

The  Circumflex  Iliac  Lymphatics  attending  the  artery  of 
the  same  name,  arise  from  the  lateral  inferior  parietes  of 
the  abdomen,  in  the  thickness  of  its  broad  muscles,  the  se- 
veral branches  assemble  into  a fevv  trunks  which  descend 
along  the  posterior  margin  of  Poupart’s  Ligament  to  termi- 
nate in  the  external  iliac  plexus. 

The  Epigastric  Absorbents  are  derived  from  the  inferior 
anterior  parietes  of  the  abdomen,  along  the  region  of  distri- 
bution of  the  epigastric  artery.  Their  trunks  coalesce  into 
larger  ones,  and  descend  along  this  artery  to  end  in  the  ex- 
ternal iliac  plexus,  near  the  crural  arch. 

The  Lumbar  Absorbents  arise  from  the  muscles  of  the 
loins,  from  the  posterior  part  of  those  of  the  abdomen,  and 
from  the  spinal  cavity.  Their  trunks  correspond  with  the 
lumbar  arteries,  and  passing  beneath  the  psoas  magnus 
muscle  towards  the  spine,  they  terminate  in  the  lumbar 
glands. 


30S 


CIllCULATOEY  SYSTEM. 


The  Intercostal  Absorbents  take  their  origin  from  the  pa« 
rietes  of  the  thorax,  and  following  the  course  of  their  respec- 
tive intercostal  arteries,  pass  through  some  small  glands  oc- 
casionally found  between  the  external  intercostal  muscles 
near  the  heads  of  the  ribs.  They  are  there  joined  by  trunks 
from  the  spinal  cavity  and  from  the  muscles  of  the  back,  and 
afterwards  passing  through  some  small  glands  on  the  front 
of  the  vertebral  column,  they  anastomose  more  or  less  with 
one  another,  and  finally  terminate  in  the  left  thoracic  duct. 
The  absorbents  of  the  pleura  costalis  and  of  the  posterior 
part  of  the  pericardium  terminate  in  the  intercostals. 

The  Internal  Mammary  Absorbents  have  their  roots  in 
the  anterior  region  of  the  parietes  of  the  abdomen,  above 
the  umbilicus,  where  they  anastomose  with  the  epigastric. 
They  ascend,  along  with  the  internal  mammary  arteries, 
behind  the  sternal  cartilages,  pass  through  some  small 
glands  and  receive  contributions  from  the  anterior  extre- 
mities of  the  intercostal  spaces.  Those  of  the  left  side,  as- 
sembling into  one  or  two  trunks,  cross  in  front  of  the  left 
subclavian  vein,  traverse  the  inferior  cervical  glands,  de- 
scend afterwards  from  this  point,  and  terminate  in  the  left 
thoracic  duct,  or  in  one  of  the.  contiguous  trunks  of  the 
venous  system.  Those  on  the  right  execute  the  same  move- 
ments, but  terminate  in  the  right  thoracic  duct,  or  in  one 
of  the  contiguous  venous  trunks  of  that  side. 

The  Absorbents  of  the  Diaphragm  are  exceedingly  nume- 
rous, and  very  much  connected  with  those  of  the  liver*  The 
anterior  ones  join  the  internal  mammary  absorbents,  while 
the  posterior  follow  the  phrenic  arteries,  or  go  to  contiguous 
trunks  belonging  to  the  intercostals.  The  front  ones  on  the 
right  side  of  course  then  terminate  in  the  right  thoracic 
duct,  while  the  remainder  go  in  the  various  routes  of  the 
absorbents,  with  which  they  are  connected,  into  the  left 
thoracic  duct.  They  are  principally  seen  on  its  upper  sur- 
face. Mr.  Cruikshank*  says,  that  he  once  saw  them  to  the 
amount  of  three  hundred  or  more,  filled  with  chyle  from 


* Loc.  cit.  p.  90. 


Absorbents  of  the  parietes  op  the  trunk.  309 

the  mesentery,  that  had  passed  through  the  substance  of *the 
liver.  Asellius  was  therefore  probably  justified  by  an  acci- 
dent of  this  kind,  in  asserting  that  the  lacteals  went  to  the 
liver. 

The  Absorbents  of  the  Female  Mammae,  like  their  arte- 
ries and  veins,  are  superficial  and  deep;  the  former  attend 
the  external  thoracic  blood  vessels,  and  the  latter  the  inter- 
nal mammary.  The  superficial  arise  from  the  circumference 
of  the  nipple,  from  the  skin  and  cellular  membrane,  and 
according  to  the  injections  of  Mr.  Cruikshank,  communicate 
freely  with  the  vesicles  of  the  tubuii  lactiferi.  They  run  to- 
wards the  axilla,  having  sometimes  to  pass  through  some 
glands  which  are  situated  half  way;  they  then  enter  the  first 
series  of  glands  of  the  axilla  in  their  direction,  and  after- 
wards others  successively,  until  they  terminate  in  the  lym- 
phatic trunks  of  the  upper  extremity,  high  up  in  the  arm- 
pit.  Some  few  of  these  superficial  vessels  ascend  over  the 
pectoralis  major  to  some  glands  in  the  neck,  just  above  the 
clavicle. 

The  deep  absorbents  of  the  mammse  arise  from  their  tho- 
racic face,  and  penetrating  the  intercostal  spaces,  join  the 
absorbents  that  attend  the  internal  mammary  artery. 

Of  the  Msorhent  Glands  in  the  Thorax. 

There  are,  as  mentioned,  a few  small  glands  in  the  inter- 
costal spaces  near  the  heads  of  the  ribs,  between  the  inter- 
nal and  external  intercostal  muscles,  intended  to  receive  the 
lymphatics  of  these  spaces.  There  are  also  several  small 
ones,  situated  on  the  front  of  the  dorsal  vertebrae,  along  the 
aorta  and  the  oesophagus,  in  the  posterior  mediastinum. 
There  are  also  from  six  to  ten  along  the  internal  mammary 
artery;  and  some  others  in  the  anterior  mediastinum,  along 
the  sterna!  face  of  the  pericardium.  They  are  said  to  be  very 
rarely  afi'ected  by  disease. 

The  most  considerable  and  striking  glands  in  -the  tho- 
rax are  those  called  Bronchial  or  Pulmonary,  which  re- 
ceive the  absorbents  of  the  lungs.  They  cluster  about  the 


;110 


CIRCULATORr  SYSTEM. 


bifurcation  of  the  trachea,  and  follow  the  bronchia  for  some 
distance  into  the  substance  of  the  lungs.  They  are  from  ten 
to  twenty  in  number,  and  vary  in  size  from  an  inch  to  a 
few  lines  in  diameter.  Till  puberty  they  have  a reddish 
colour,  but  afterwards  they  become  gray,  and  finally  black, 
following,  in  these  respects,  the  change  of  colour  in  the 
lungs.  According  to  Mr.  Pearson,  their  complexion  de- 
pends  upon  the  deposite  of  pure  carbon. 

In  pulmonary  consumption  these  glands  are  always  en- 
larged, and  look  scrofulous. 

SECT.  VIII. or  THE  THORACIC  DUCTS. 

The  Left  Thoracic  Duct  {Ductus  Thoracicus  Sinister)  is 
the  main  stream  of  the  absorbent  system,  to  which  almost  all 
the  others  are  but  tributary,  and  by  divers  routes  ultimately 
find  their  way  into  it.  It  begins  about  the  second  or  third 
lumbar  vertebra,  in  front  of  its  body.  Shortly  after  its  com- 
mencement, while  still  in  the  abdomen,  it  suffers  a dilatation 
more  or  less  considerable,  and  varying  in  its  shape  in  differ- 
ent subjects.  This  is  called  the  Reservoir  of  Pecquet,  or  the 
Receptaculum  Chyli;  the  dilatation,  however,  is  frequently 
absent  and  does  not  seem  to  be  an  essential  part  of  the  struc- 
ture j in  our  preparations  at  the  University  some  have  it, 
and  others  have  it  not. 

The  thoracic  duct  enters  the  thorax  between  the  crura  of 
the  diaphragm,  to  the  right  of,  and  behind  the  aorta;  it  then 
ascends  on  the  front  of  the  dorsal  vertebrje,  between  the 
aorta  and  the  vena  azygos,  in  front  of  the  right  intercostal 
arteries,  and  behind  the  oesophagus.  At  the  fourth  dorsal 
vertebra  it  begins  to  incline  in  its  ascent  to  the  left  side,  and 
then  ascends  into  the  neck  near  the  head  of  the  first  rib;  it 
rises  commonly  as  high  as  the  upper  margin  of  the  seventh 
cervical  vertebra;  it  then  turns  downwards  and  forwards, 
over  the  left  subclavian  artery  within  the  scaleni  muscles, 
and  finally  discharges  into  the  angle  of  junction  of  the  left 
subclavian  and  internal  jugular  veins. 

The  preceding  is  the  most  simple,  and  perhaps  the  most 
common  form,  under  which  the  thoracic  duct  is  presented, 


THORACIC  DUCTS. 


311 


but  varieties  are  continually  occurring  in  its  place  and  mode 
of  origin,  in  its  trunk,  and  its  manner  and  place  of  termina- 
tion. It  commonly  begins  by  the  union  of  three  absorbent 
trunks;  one  for  each  side  of  the  pelvis,  along  with  the  corres- 
ponding lower  extremity;  and  a middle  one  for  the  chylife- 
rous  vessels,  which  unites  with  the  common  trunk  of  the 
other  two  a few  lines  above  its  point  of  formation;  on  other 
occasions,  the  chyliferous  trunks  join  it  in  a confused  manner 
by  nine  or  ten  distinct  channels.  Sometimes  an  intricate 
plexus  of  several  large  trunks,  derived  from  the  lumbar  and 
mesenteric  glands;  by' the  gradual  reduction  of  the  number 
of  meshes  from  the  successivejoining  of  trunks;  begins  to  as- 
sume, at  the  crura  of  the  diaphragm,  the  form  of  a solita- 
ry trunk,  which  is  the  thoracic  duct.  The  trunk  of  the 
duct  is  also  disposed  to  keep  up  the  anastomosing  plan,  even 
in  the  thorax;  we  hence  see  it  sometimes  dividing  itself  into 
two  or  three  channels  of  equal  sizes,  which  unite  again  after 
a shorter  or  longer  distance,  and  perhaps  in  a little  space 
repeat  the  same  arrangement:  sometimes  a small  arm  is  sent' 
off,  which  runs  alone  for  an  inch  or  two,  and  joins  into  the 
parent  stream;  sometimes  spiral  turns  are  adopted  by  the 
thoracic  duct,  sometimes  nodosities,  or  small  pouches,  are 
formed  on  its  sides;  sometimes  it  is  dilated  at  intervals  in.its 
whole  circumference.  Sometimes  it  splits  into  several  chan- 
nels at  its  termination;  one  channel  terminating  in  one  vein 
and  another  in  a contiguous  one,  of  the  several  trunks  form- 
ing the  vena  innominata;  on  other  occasions,  instead  of  en- 
tering into  a venous  trunk  of  the  left  side,  it  goes  into  the 
corresponding  one  of  the  right. 

Commonly  it  is  about  the  size  of  a large  crow  quill,  but 
sometimes  as  large  as  a goose  quill,  or  even  still  more  volu- 
minous, seeming  to  be  in  a varicous  state,  of  which  Mr. 
Cruikshank  mentions  an  example  where  it  was  half  an  inch 
in  diameter,  and  took  two  pounds  of  mercury  to  fill  it. 
There  is  generally  a pair  of  valves  at  the  termination  of  the 
thoracic  duct,  or  if  it  be  divided  into  several  streams  there 
is  a pair  at  the  embouchure  of  each,  to  keep  the  venous 
blood  out  of  it.  There  are  also  valves  in  its  length,  but 
they  are  not  numerous,  and  vary  in  different  subjects. 


312 


CIRCULATORY  SYSTEM. 


The  thoracic  duct  is  the  grand  outlet  for  the  lymphatics 
of  the  left  side  of  the  head  and  neck,  of  the  left  superior  ex- 
tremity, of  the  intercostals,  of  the  left  side  of  the  thorax,  of 
the  viscera  of  the  abdomen,  and  of  the  inferior  extremities. 
Though  those  of  the  viscera  of  the  abdomen  and  of  the  lower 
extremities  have  this  route,  yet  from  the  observations  of  Mr. 
Lippi,  of  Florence,  as  mentioned,  they  have  also  some  more 
direct  m.eans  of  getting  into  the  general  circulation.  For 
example,  he  has  found  several  large  lymphatic  trunks  emp- 
tying into  the  ascending  cava,  one  of  them  opposite  the 
third  lumbar  vertebra;  another  into  the  primitive  iliac  vein: 
he  has  also  found  some  of  the  lymphatics  of  the  liver  dis- 
charging into  the  vena  portarum. 

The  Right  Thoracic  Duct,  {Ductus  Thoracicus  Dexter,) 
as  it  is  called,  but  more  properly  the  Right  Brachio-cepha- 
lic,  after  the  name  given  by  M.  Chaussier  to  the  vein,  is  not 
more  than  an  inch  long,  and  descends  to  empty  itself,  as  men- 
tioned, into  the  junction  of  the  right  internal  jugular  with 
the  right  subclavian  vein.  It  is  derived  from  the  lympha- 
tic trunks  of  the  right  side  of  the  head  and  neck,  from  the 
right  upper  extremity,  the  superficial  lymphatics  of  the  right 
side  of  the  thorax,  the  lymphatics  of  the  right  lung,  of  the 
right  side  of  the  diaphragm,  and  some  of  those  of  the  right 
side  of  the  liver,  the  courses  of  all  of  which  have  been  de- 
tailed. 

Though  the  single  trunk  is  formed  from  these  several  tri- 
butary streams,  yet  the  latter  have  sometimes  several  em- 
bouchures into  the  venous  system  at  or  near  the  point  men- 
tioned, and,  as  on  the  other  side  of  the  body,  there  is  a pro- 
per security  by  valves  from  the  introduction  of  blood  into 
them. 

There  is  always  an  ample  system  of  anastomosis,  not  only 
between  the  branches  which  concur  to  form  the  right  and 
left  thoracic  ducts,  but  even  between  the  ducts  themselves,’^' 
so  that  if  one  be  occluded  or  impeded,  its  circulation  can  be 
turned  into  the  other,  as  in  the  case  of  veins. 

* Meckel,  Man.  D’Anat.  tom.  ii.  p.  581 


BOOK  IX. 


NERVOUS  SYSTEM. 

PART  I. 

On  the  General  Anatomy  of  the  JYervoiis  System. 

The  nervous  system  in  man,  and  other  vertebrated  ani- 
mals, consists  in  two  portions  of  dissimilar  forms:  one  is 
spheroidal,  elongated  at  its  base  into  a cylindrical  process, 
and  is  contained  in  the  cranium  and  in  the  spinal  canal;  the 
other  is  an -assemblage  of  arborescent  rays,  which  proceed 
from  different  points  of  the  first  portion,  to  every  part  of 
the  body.  The  first  portion  is  the  Central  or  Internal  part 
of  the  nervous  system,  composed  of  the  Brain  and  Spinal 
Marrow,  while  the  radiating  portion  is  called  the  External 
or  Peripheral,  and  consists  in  the  Nerves  of  the  brain  and 
spinal  marrow. 

The  nervous  system  is  remarkable  for  its  symmetry;  as 
it  is  universally  double,  it  very  seldom  happens  that  any 
striking  difference  of  it  on  the  two  sides  of  the  body  is  ma- 
nifested, particularly  as  regards  its  Central  portion;  it  is 
said,  however,  that  aberrations,  in  this  respect,  are  more 
common  in  man  than  in  other  mammiferous  animals. 

The  Central  Portion  of  the  Nervous  System  is  composed 
of  two  kinds  of  substance,  distinguished  by  their  colour  and 
relative  situation:  one  is  improperly  enough  called  Medul- 
lary {Substantia  Medullaris)  but  as  the  name  is  now  sanc- 
tioned by  universal  usage,  it  is  impossible  to  dispense  with 
it.  The  other  is  called  Cineritious  {Substantia  Cinerea,) 
with  perhaps  sufficient  propriety,  from  its  colour.  They  are 
both  of  a soft  pulpy  consistence,  and  constitute  the  chief 
mass  of  the  brain  and  spinal  marrow:  some  anatomists  have 
VoL.  II. — 40 


314 


^KKVOUS  SYSTEM. 


desired  to  add,  fi’om  some  slight  distinction  of  colour,  two 
other  substances,  a yellow  and  a black,  but  that  seems  un- 
necessary, and  has  not  been  acknowledged.  These  sub- 
stances differ  from  one  another  in  regard  to  their  quantity, 
the  medullary  being  more  abundant  than  the  cineritious;  it 
is  also  harder,  and  receives  fewer  vessels.  But  the  atoms  of 
both  have  the  same  elementary  form,  that  of  globules  united 
by  a semi-fluid  substance;  the  shape  of  these  globules,  as 
well  as  their  size  and  degree  of  solidity,  are  not  yet  ascer- 
tained.'^ 

The  MeduHary  Matter,  when  quite  fresh  and  scraped  in 
particular  directions,  has  a fibrous  appearance,  which  may 
be  rendered  still  more  distinct  by  hardening  it  in  alcohol, 
in  boiling  oil,  in  a solution  of  the  neutral  salts,  or  in  diluted 
mineral  acids.  If  an  attempt  be  then  made  to  tear  it,  it  will 
be  immediately  perceived  that  the  fibres  separate  in  a fixed 
dii'ection,  and  in  no  other.  These  fibres,  when  viewed  with 
a microscope,  seem  to  consist  of  fibrillae  too  fine  to  admit  of 
any  rigid  conclusions  in  regard  to  their  size,  and  which 
are,  in  some  instances,  parallel,  in  others,  concentric,  and 
in  others,  diverging  or  converging. t 

The  two  substances  are  variously  placed  in  different  parts 
of  the  nervous  system:  the  surface  of  the  cerebrum  and  of 
the  cerebellum  is  formed  by  the  cineritious  matter,  and  the 
interior  principally  of  medullary;  while  the  surface  of  the 
pons,  of  the  crura,  and  of  the  spinal  marrow,  is  medullary, 
and  their  interior  cineritious.  Again,  in  other  points,  they 
are  intermixed.  The  medullary  matter  is  always  so  arranged 
that  it  is  never  interrupted,  but  forms  a continuous  whole; 
while  the  cineritious  is  in  detached  masses,  and  is  found 
wherever  the  central  extremities  of  the  nerves  are  implanted, 
or  where  there  is  an  increase  of  medullary  fibres.  Some 
anatomists  have  even  supposed  that  it  existed  at  the  peri- 

* Sir  Evd.  Home  and  Mr.  Bauer,  Phil.  Transactions.  London,  An.  1821. 
Milne  Edwards,  Thesis  on  the  Elementaiy  Tissues  of  Animals.  Pai'is,  1823. 

f See  Lessons  on  Practical  Anatomy,  by  W.  E.  Horner.  Brain  accordint^ 
to  Gall  and  Spurzheim. 


GENERAL  ANATOMT  OF  THE  NERVOUS  SYSTEM.  315 

pheral  extremities  of  the  nerves,  and  particularly  in  the  retc 
mucosum  of  the  skin. 

The  fibrillae  of  the  medullary  tissue  are  united  by  a very 
fine  and  thin  cellular  substance,  which  may  be  seen  by  tear- 
ing them  apart.  This  cellular  substance  is  more  condensed 
near  the  surface  of  the  brain,  where  it  is  formed  into  a highly 
vascular  membrane,  the  pia  mater,  and  is  continued  along 
the  nerves  as  a neurileme,  or  covering  to  them. 

The  central  nervous  system  is  abundantly  supplied  with 
blood  vessels,  but  lymphatic  trunks  have  not  yet  been  in- 
jected in  it. 

The  Peripheral  Portion  of  the  Nervous  System  or  the 
Nerves,  are  formed  by  parallel  fasciculi  of  fibres,  percepti- 
ble to  simple  inspection,  which  may  be  reduced  into  fibrillse, 
and  then  again  into  filaments  as  small  as  the  thread  of  a silk 
worm.  The  finest  filament  is  enclosed  in  its  appropriate 
sheath,  so  that  the  latter  is  a tube  filled  with  nervous  matter. 
The  nervous  matter  is  soluble  in  an  alkali,  and  in  that  way 
may  be  removed;  the  canals  may  then  be  filled  with  quick- 
silver or  air,  and  their  existence  demonstrated.  On  the 
other  hand,  nitric  or  muriatic  acid  dissolves  the  sheath,  but 
hardens  the  nervous  matter,  and  renders  it  more  distinct,  so 
that  the  finest  filaments  are  made  obvious.  * In  either  case 
it  is  evident  that  the  shape  of  the  nerve  is  preserved.  These 
filaments  are  supposed  to  be  precisely  the  same  with  the 
fibres  of  the  brain,  excepting  that  their  sheaths  keep  them 
more  distinct  from  one  another. 

The  Sheath  of  the  nerves,  or  the  Neurileme  {^Neurilemma) 
forms  a general  envelope  to  the  nervous  fasciculi,  as  well  as 
a particular  one  to  each  fibre,  and  is  continuous,  at  its  cen- 
tral extremity,  with  the  pia  mater.  Its  canals  branch  off 
and  unite  again  at  intervals,  forming  a species  of  reciprocal 
anastomosis,  sufficiently  represented  by  the  plan  of  the  large 
nervous  plexuses,  as  they  occur  in  various  parts  of  the  body. 
It  is  the  general  envelope  which  is  obviously  continuous  with 
the  pia  mater,  but  the  particular  sheaths  of  the  finer  fibres 


Reil,  de  Struct.  Nerv. 


31G 


NERVOUS  SYSTEM- 


are  lost,  insensiblj'-,  so  that  these  fibres  appear  naked  in  the 
centre  of  the  nerve,  at  its  central  extremity-  The  same 
destitution  of  neurileinatic  covering  is  observable  at  the  pe- 
ripheral extremities  of  the  nerves,  wherever  the  latter  can 
be  traced.  The  interior  of  these  canals  is  traversed  by  pro- 
cesses, which  cross  the  nervous  matter  and  sustain  it.  From 
the  increase  in  size,  the  additional  solidity,  and  the  close 
adhesion  of  the  nerves  to  the  dura  mater,  where  they  pass 
out  of  their  several  foramina  in  the  spine  and  cranium,  there 
is  no  doubt  that  the  dura  mater  contributes  to  the  neurileme, 
though  its  structure  is  altered  and  made  much  less  dense. 
The  best  evidence  of  this  is  the  sheath  of  the  optic  nerve, 
and  of  the  spinal  nerves.  This  opinion,  advanced  by  the 
ancients,  has  been  strongly  contested  by  Haller,*  and  by 
Zinn.t  The  tunica  arachnoidea  is  too  fine  to  admit  of  any 
positive  opinion  about  the  extent  to  which  it  follows  the 
nerves. 

The  neurileme  has  but  little  contractility,  is  solid  and 
difficult  to  tear,  and  is  supposed  to  be  the  secretory  organ 
of  the  medullary  substance. 

The  nervous  fasciculi  are  moreover  held  together  by  cel- 
lular substance,  which  has  in  the  progress  of  life,  a tenden- 
cy to  the  deposite  of  fat.  This  cellular  substance,  in  neu- 
ralgic affections,  is  subject  to  infiltrations  and  redness, 
whereby  it  becomes  hard.  This  circumstance  has  induced 
pathologists  to  consider  the  pain  as  depending  upon  its  in- 
flammation, f; 

The  optic  nerve,  owing  to  the  size  of  its  canals,  furnishes 
the  best  example  of  structure,  and  tbe  nerves  of  the  mus- 
cles are  next.  There  are,  however,  some  peculiarities  in 
different  nerves;  as  the  observations  of  Sir  Everard  Home 
have  ascertained  that  the  medullary  filaments  of  the  optic 
nerve  augment  in  numbers  and  diminish  in  volume,  from 
its  origin  towards  its  termination.  The  principal  light 
thrown  upon  these  minute  and  interesting  points  of  nervous 
organization,  has  been  derived  from  the  researches  of  Reil.§ 

* Prim.  Lin.  f Memoires  de  Berlin,  1753. 

Bectird,  Anat.  Gen.  p.  665. 

§ Reil,  de  Sti-uctm-a  Nervorum.  Ilalie  Saxonum,  1796. 


general  ANATOaxr  OF  THE  NERVOUS  SYSTEM.  317 

In  addition  to  the  preceding  structure,  the  nerves  present 
a satin-like  undulated  surface,  with  small  bands  that  pass 
somewhat  spirally  and  in  a zig-zag  direction.  The  latter 
appearance  is  illusory,  and  depends  upon  the  contraction  or 
shortening  of  the  nerve  when  not  stretched;  its  seat  is  in 
the  neurileme,  and  it  accordingly  disappears  upon  exten- 
sion. 

The  nerves  abound  in  blood  vessels;  when  a vascular 
trunk  reaches  them,  one  of  its  branches  ascends  and  ano- 
ther descends,  and  if  successfully  injected,  the  neurileme 
is  covered  by  its  capillary  ramifications.  As  in  the  brain, 
the  lymphatics  have  not  yet  been  injected. 

There  are  three  modes  by  which  the  nervous  fasciculi 
unite  with  one  another;  anastomosis;  plexus,  and  ganglion. 
Anastomosis  is  the  junction  of  the  filaments,  either  of  the 
same  nerve  or  of  different  nerves,  and  the  examples  of  it 
are  very  abundant.  Plexus  is  an  anastomosis  on  a larger 
scale,  and  occurs  between  the  larger  fasciculi  of  the  same 
nerve,  or  of  different  nerves,  whereby  a very  complete  in- 
tertexture of  their  fibres  occurs.  Ganglions  are  knots  which 
occur  in  the  course  of  nerves,  whereby  they  have,  for  the 
time,  a great  augmentation  of  volume. 

The  Ganglions  have  a great  variety  of  form  and  size: 
they  are  parabolic,  circular,  crescentic,  and  so  on;  and,  in 
their  general  appearance,  hardness,  and  colour,  resemble 
somewhat  lymphatic  glands.  Their  structure  is  intricate, 
and  as  yet  rather  unsettled.  When  submitted  to  macera- 
tion, they  are  resolved  into  two  kinds  of  substance;  one  is 
filamentous  and  continuous  with  the  nerves  adhering  to  the 
ganglion,  and  the  other  is  gelatinous  and  of  a reddish  ash 
colour.  The  filaments,  in  penetrating  the  ganglions,  are 
deprived  of  their  neurileme,  which  is  continued  into  a sort 
of  capsule  that  surrounds  the  ganglions.  They  pass  unin- 
terruptedly through  the  ganglion,  and  therefore  continue 
the  several  nervous  cords  into  one  another;  but  in  a compli- 
cated way.  The  nature  of  the  gelatinous  substance  is  not 
fully  ascertained;  by  some,  and  Scarpa  among  others,  it  is 
thought  to  be  fat.  The  ganglions,  like  other  parts  of  the 
nervous  system,  are  very  vascular. 


NEKVOUS  SYSTEM. 


olb 

The  Ganglions  are  said  to  be  simple  and  compound;  the 
first  is  where  a single  nerve  produces  the  ganglion,  and  the 
second  where  the  filaments  of  two  or  more  nerves  concur 
to  form  it.  The  simple  ganglions  are  invariable  in  their 
form  and  situation,  and  belong  to  the  spinal  marrow,  being 
formed  upon  the  posterior  fasciculi  alone:  this  fact  was  first 
pointed  out  by  Haase,^  and  has  been  subsequently  confirmed 
by  the  observations  of  Scarpa  and  of  Prochaska,  and  by  the 
admission  of  anatomists  -generally.  Their  exterior  enve- 
lope is  continuous  with  the  dura  mater,  and  the  internal 
with  the  pia  mater,  from  whence  they  have  more  firmness 
than  other  ganglions.  The  composite  ganglions  are  found 
at  divers  stations  about  the  body. 

The  Nervous  Systfem  is  the  seat  of  intelligence,  and  also 
extends  its  physical  influence  to  every  part  of  the  body. 
Both  the  one  and  the  other  qualities  reside  in,  its  central 
portion;  the  first  in  the  brain,  and  the  second  in  the  spinal 
marrow.  When  the  communication  between  the  brain  and 
the  spinal  marrow  is  interrupted  by  an  accident,  or  in  an 
experiment,  the  difference  between  the  influence  of  the  two 
is  strongly  marked :t  the  influence  of  the  brain  seeming  to 
be  entirely  intellectual,  so  that  an  animal  will  even  bear  its 
removal  without  immediate  death;  while  the  influence  o^ 
the  spinal  marrow  is  so  indispensable  to  life,  that  its  de- 
struction is  followed  by  instantaneous  and  perfect  death.  1; 
Under  common  healthful  circumstances,  however,  the  two 
seem  to  exercise  a mixed  influence  on  all  parts  of  the  body; 
as,  for  example,  upon  the  reception  of  distressing  intelli- 
gence, the  stomach  ejects  its  contents,  or  refuses  to  receive 
more;  alarming  intelligence  causes  the  heart  to  flutter  and 
to  palpitate,  and  both  the  bladder  and  the  intestines  to  eva- 
cuate their  contents.  On  the  contrary,  a proper  degree  of 
corporeal  exertion  strengthens  the  intellectual  operations, 
w'hile  its  excess  debilitates  them.  That  these  several  ner- 

* De  Gang-liis  Nervorum.  Leipsick,  1772. 

j Legallois  on  the  Principle  of  Life. 

i Observ.  and  Exper.  on  the  Nervous  System,  by  W.  E.  Horner.  Sec 
Chapman’s  Med.  and  Phvs.  Journal,  vol.  i.  p.  285. 


GENERAL  ANATOMY  OF  THE  NERVOUS  SYSTEM.  31 1) 

vous  influences  are  seated  in  the  central  part  of  the  nervous 
system,  seems  proved  by  the  fact,  that  where  there  has  been 
a congenital  deficiency  of  all  the  limbs,  or  an  accidental  one, 
which,  of  course,  removes  a very  considerable  portion  of 
the  peripheral  part  of  the  nervous  system,  animal  life  and 
the  intellectual  operations  have  still  gone  on  vigorously. 

The  following  are  some  of  the  physical  functions  over 
which  the  nervous  system  seems  to  preside. 

Digestion;  the  whole  alimentary  canal  from  the  mouth  to 
the  anus,  is  under  this  influence:  first  of  all  in  mastication, 
then  in  swallowing,  afterwards  in  digestion  and  the  absorp- 
tion of  chyle,  and  finally  in  the  passing  of  the  effete  matter 
out  of  the  body.  It  has  been  sufficiently  proved,  by  the 
experiments  of  several  physiologists,  that  the  section  of  the 
par  vagum  destroys  the  faculty  of  digestion. 

Respiration;  the  mechanical  act  of  this  process,  that  by 
which  the  cavity  of  the  thorax  is  enlarged  so  as  to  admit  of 
the  introduction  of  air,  evidently  depends  upon  the  phrenic 
and  the  intercostal  nerves.  If  also  the  nerves  which  sup- 
ply the  structure  of  the  lungs  be  alone  intercepted,  as  the 
par  vagum,  either  by  ligature  or  section,  the  changes  on 
the  blood  produced  by  respiration  cease  and  the  animal 
dies. 

Secretion,  exhalation,  absorption,  and  animal  heat,  seem 
also  to  be  dependent  upon  the  integrity  and  the  activity  of 
nervous  influence.  The  action  of  the  heart,  sensation,  and 
voluntary  motion,  are  in  the  same  predicament. 

The  manner  in  which  these  several  kinds  of  innervation 
is  produced,  is  unintelligible  One  has  supposed  it  to  con- 
sist in  a vibration  of  the  elementary  fibres  of  the  nerves; 
another  in  an  agitation  of  its  elastic  globules;  another  in  the 
transmission  of  an  imponderable  fluid,  as  aether,  magnetism, 
electricity,  and  galvanism.  Reil  has  proposed,  on  this  sub- 
ject, what  has  been  termed  a chemico-vital  hypothesis:  ac- 
cording to  him,  the  general  action  of  parts  depends  upon 
their  form  and  composition;  consequently,  when  the  two 
latter  vary,  the  first  does  also.  M.  Bedard*  inclines  to 


* Anat.  Gen. 


320 


NERVOUS  SYSTEM. 


the  opinion,  that  “ the  nervous  system  is  the  elaborator  and 
conductor  of  an  imponderable  agent;  and  like  electricity  or 
magnetism,  that  by  it  we  can  explain  all  the  phenomena  of 
innervation; — The  relation  between  the  benumbing  influ- 
ence of  electric  fish  and  galvanic  phenomena  on  one  part, 
and  ordinary  nervous  action  on  the  other; — The  practicabili- 
ty of  causing  galvanic  phenomena  by  the  nerves  and  muscles 
alone; — The  possibility  of  producing  muscular  contraction, 
the  chymifiant  action  of  the  stomach,  the  respiratory  action 
of  the  lung,  &c.  in  substituting  a galvanic  for  a nervous  in- 
fluence;— The  existence  of  a nervous  atmosphere,  acting  at 
a distance  around  the  nerves  and  muscles,  and  between  the 
ends  of  divided  nerves; — The  wrinkling  of  muscular  fibres 
in  contraction,  and  the  relation  of  the  finest  transverse  ner- 
vous fibres  with  those  wrinkles;  phenomena  of  innervation 
which  nearly  approach  certain  electro-magnetical  ones.  ” 
This  subtle  fluid,  according  to  M.  Bedard,  seems  to  be 
formed  every  where,  but  principally  in  places  where  there 
is  much  vascularity  along  with  the  ash-coloured  substance- 
It  impregnates  all  the  humours  and  _ organs.  The  blood 
seems  to  be  especially  endowed  with  it,  and  owes  to  it  the 
properties  which  distinguish  it  during  life.  In  conse- 
quence of  which,  life  is  essentially  connected  to  the  recip- 
rocal action  of  the  blood  upon  the  nervous  substance,  and  of 
the  nervous  substance  upon  the  blood.* 

Mr.  Charles  Bell,  of  London,  has  lately  presented  in  a 
very  interesting  light  certain  functions  of  the  nervous  sys- 
tem :t  by  his  researches  it  appears,  that  besides  the  nerves 
of  vision,  smell,  and  hearing,  there  are  four  other  systems, 
having  different  functions,  and  extended  through  the  whole 
frame.  Those  of  Sensation;  of  Voluntary  Motion;  of  Re- 

* M.  Rolando  (Saggio  sulla  vera  struttura  del  cervello,  e sopra  le  fun- 
zioni  del  sistema  nervoso,  1809,  Beclard,  p.  622.)  has  been  so  much  taken 
with  the  galvanic  manifestations  of  the  nei-vous  system,  that  in  the  lami- 
nated arrangement  of  the  cerebellum  he  lias  only  seen  a modification  of  the 
Voltaic  pile.  In  the  convolutions  of  the  cerebrum,  he,  no  doubt,  would 
have  recognised,  on  acquaintance  with  this  powerful  instrument,  the  Spi- 
ral Calorimotor  of  Professor  Hare  of  this  University. 

f Exposition  of  the  Natural  System  of  the  Nerves  of  the  Human  Bod’" 
Philad,  1825, 


GENERAL  ANATOMV  OF  THE  NERVOUS  SYS'^EM.  321 

spiratory  Motion;  and  nerves,  which  give  unity  to  the  body 
in  harmonizing  the  functions  of  nutrition,  growth,  and  de- 
cay, or  whatever  else  is  indispensable  to  animal  existence. 

According  to  this  theory,  the  several  filaments  of  a nerve 
exercise  one  or  the  other  function,  but  only  the  one;  these 
dissimilar  filaments  being  bound  up  in  the  same  fasciculus, 
constitute  a nerve  or  fascis,  and  they  never  exchange  power 
with  one  another:  their  anatomical  differences,  however, 
are  such,  as  not  to  make  obvious  one  kind  of  filaments  from 
the  others.  Several  columns  of  nervous  matter  form  the  spi- 
nal marrow,  six  in  all,  three  on  each  side;  the  anterior  for 
voluntary  motion,  the  posterior  for  sensation,  and  the  mid- 
dle for  respiration;  and  it  is  probable  that  still  more  ma}r 
be  found  out.  The  first  and  the  third  ascend  into  the  brain, 
and  the  middle  stops  short  in  the  medulla  oblongata,  hence 
the  function  of  respiration  goes  on  so  long  as  the  medulla 
oblongata  remains  entire.  These  few  principles,  supported 
by  several  experiments,  have  enabled  Mr.  Bell  to  bring  for- 
ward a system  of  no  small  importance  on  the  anatomy  and 
physiology  of  the  nervous  system.* 

The  development  of  the  nervous  system  is  amongst  the 
earliest  processes  in  the  distinct  evolution  of  the  foetal  oi’- 
gans.t  At  the  end  of  the  first  month,  when  the  head  is  a 
mere  swelling  of  one  end  of  the  small  maggot-like  being, 
the  brain  and  the  spinal  marrow  are  not  by  any  means  dis- 
tinct, but  the  parts  being  transparent,  a limpid  fluid  holds 
their  place.  About  the  fifth  or  sixth  week,  the  embryo 
haVing  acquired  a length  of  five  or  six  lines,  the  rudiments 
of  the  brain  appear  as  vesicles  containing  a whitish  and  al- 
most diaphanous  fluid,  while  the  spinal  marrow  represents 
a long  canal  containing  the  same,  and  communicating  with 
the  cerebral  vesicles. 

* The  same  subject  has  been  taken  up,  in  an  inaugural  thesis,  by  a zea- 
lous asid  intelligent  graduate  of  the  University,  and,  by  a series  of  inge- 
nious experiments,  seems  to  have  been  generally  proved  and  illustrated. 
Chapman’s  Med.  and  Phys.  Journal,  1825;  vol.  vi.  p.  240,  Remarks  on  some 
of  the  Nervous  Functions,  by  J.  P.  Hopkinson. 

-(•  Anat.  du  Cerveau,  par  F.  Tiedemann,  ti-aduit  par  Jourdan,  Paris,  1823, 
Anat.  Comp,  du  Cerveau,  par  E.  R.  A.  Serres,  Paris,  1824. 

VoL.  II.— 41 


322 


KEKVOUS  SYSTEM. 


In  the  early  part  of  the  third  month,  when  the  embryo 
is  about  twelve  lines  long,  the  brain  and  spinal  marrow  be- 
gin to  show  very  distinctly  the  rudiments  of  the  several 
cavities,  elevations,  and  fasciculi,  which  mark  their  subse- 
quent mechanical  arrangement  of  surface;  and  from  this  pe- 
riod it  is  no  longer  difficult  to  trace  the  successive  develop- 
ment of  each  part  to  the  degree  of  perfection  which  it  has 
at  the  time  of  birth. 

From  the  many  observations  made  by  Tiedemann  on 
these  points,  he  has  deduced  the  conclusion,  that  the  brain 
is  produced  by  the  superior  part  of  the  spinal  marrow,  that 
is  to  say,  by  the  medulla  oblongata,  which  grows  and  is  de- 
veloped for  the  purpose.  That  this  is  proved,  in  the  ex- 
tension upwards  and  forwards  of  the  two  principal  fasciculi 
of  the  spinal  marrow,  and  by  a canal  which  is  found  in  the 
spinal  marrow  of  the  foetus,  being  extended  to  the  fourth 
and  even  to  the  third  ventricle;  also,  by  the  cerebellum 
proceeding  evidently  from  the  same  source,  since  its  two 
crura  may  be  traced  growing  from  it,  and  subsequently 
uniting  over  the  fourth  ventricle,  so  as  to  form  the  especial 
structure  of  the  cerebellum;  also,  by  the  tubercula  quadri- 
gemina  being  derived  from  the  corpora  olivaria  of  the  me- 
dulla oblongata,  and  by  the  thalami  and  the  corpora  striata 
proceeding  from  the  corpora  pyramidalia,  and  finally  forming 
the  hemispheres  of  the  cerebrum. 

In  addition  to  the  preceding  proofs,  comparative  anatomy 
furnishes  other  illustrations.  The  brain  becomes  more  and 
more  complex  as  one  ascends  from  fish  to  reptiles,  from 
the  latter  to  birds,  and  then  to  mammiferous  animals.  The 
spinal  marrow  is  very  voluminous  in  the  inferior  animals, 
while  the  brain  only  forms  an  appendix  to  it;  whereas,  if 
the  spinal  marrow  were  an  appendix  to  the  brain,  we  ought 
to  find  the  last  of  a prior  formation  in  foetuses,  and  also  in 
a perfect  state  in  the  lower  animals,  before  a medulla  spi- 
nalis could  be  found. 


* Tiedeman,  loc.  cit.  p.  157. 


BOOK  IX. 


PART  II. 

On  the  Special  Anatomy  of  the  Central  Portion  of  the 
JVervous  System. 


CHAPTER  I. 

OF  THE  SPINAL  MARROW  AND  ITS  MEMBRANES. 

The  Spinal  Marrow  {Medulla  Spinalis)  though  com- 
monly described  after  the  brain,  as  a continuation  or  appen- 
dage of  it,  bas  precedence,  as  seen  both  in  the  period  of 
its  formation  in  the  embryo,  and  in  its  importance  to  the 
functions  of  the  animal  system;  it  will  consequently  be  use- 
ful to  give  it  that  priority  in  description  to  which  its  natu- 
ral rank  entitles  it. 

SECT.  I. op  THE  SPINAL  MARROW'. 

It  is  placed  within  the  vertebral  cavity,  and  extends  from 
the  first  vertebra  of  the  neck  to  the  first  or  second  vertebra 
of  the  loins  inclusively.  It  is  surrounded  by  three  mem- 
branes, of  which  the  Dura  Mater  is  external,  the  Pia  Mater 
internal,  and  the  Tunica  Arachnoidea,  betw^een  the  other 
two.  Its  general  form  is  cylindrical,  yet  it  has  slightly  the 
appearance  of  being  flattened  both  behind  and  before.  It 
departs  also  from  the  strict  cylindrical  shape  by  being  en- 
larged or  swollen  at  particular  points.  One  of  these  en- 
largements occurs  in  the  neck,  where  the  canal  is  formed 


324 


NERVOUS  SYSTEM. 


by  the  five  lower  cervical  vertebrse  and  the  axillary  plexus 
of  nerves  is  given  ofif.  The  enlargement  is  in  the  transverse 
direction  or  axis  of  the  spinal  marrow,  but  not  in  its  thick- 
ness, and  terminates  gradually  both  above  and  below. 
The  medulla  spinalis  afterwards  continues  small,  with  very 
slight  undulations  or  nodosities,  until  within  three  or  four 
inches  of  its  lower  extremity,'  when  it  again  enlarges.  The 
enlargement  here,  though  sufficiently  obvious,  is  not  equal 
in  actual  magnitude  to  that  in  the  neck,  and  is  the  place 
from  which  all  the  lumbar  nerves  and  the  three  superior 
sacral  proceed.  It  is  then  brought  gradually  to  a point 
somewhat  blunted,  which  most  commonly  does  not  descend 
below  the  first  lumbar  vertebra.  The  point  is  in  some  rarei 
cases  bifurcated,  and  by  a transverse  fissure  converted  into 
a tubercle. 

The  spinal  marrow,  besides  terminating  so  much  above 
the  lower  end  of  the  spinal  canal,  is  much  smaller  in  its  dia- 
meter, even  with  the  addition  of  its  membranes,  than  the 
canal.  This  circumstance  prevails  especially  in  the  neck, 
and  in.  the  loins,  where  much  motion  is  experienced;  and 
consequently  a provision  is  thus  made  against  any  injury  to 
it  from  pressure. 

The  Medulla  Spinalis  is  marked  off  longitudinally  into 
two  symmetrical  parts  by  one  fissure  in  front  and  another 
behind,  both  of  which  extend  its  whole  length,  and  are 
placed  exactly  in  its  middle.  The  contiguous  edges  or  sur- 
faces of  each'of  these  fissures  adhere  so,  that  it  requires  a 
slight  maceration  or  dissection  to  render  them  evident.  The 
posterior  fissui’e  is  decidedly  deeper  at  its  upper  part  than 
the  anterior,  but  tlie  latter  in  return  is  somewhat  broader. 
The  difference  in  depth,  however,  is  unimportant,  as  sub- 
jects are  frequently  met  with  in  which  it  is  not  appreciable. 

Moreover,  on  each  side  of  the  Medulla  Spinalis  there  is  a 
lateral  fissure.  It  is  not  precisely  in  the  middle,  but  some- 
what posterior,  and  penetrates  inwards  an'’  forwards.  In 
many  instances  it  is  merely  a simple  superficial  depression, 
much  less  deep  than  either  of  the  former.  It  does  not  run 


SPINAL  MARROW. 


325 


the  whole  length  of  the  medulla  spinalis,  but  terminates 
somewhere  in  the  upper  part  of  its  thoracic  portion  by  join- 
ing with  its  fellow,  after  having  converged  regularly  towards 
it.*  The  different  opinions  of  anatomists  on  the  existence 
of  these  two  fissures  may  be  accounted  for  by  their  being 
readily  found  in  early  life,  while  they  are  obliterated  or 
very  indistinct  in  old  age.  These  lateral  fissures  should  be 
carefully  distinguished  from  two  others,  also  on  either  side, 
one  before  and  the  other  behind,  which  extend  the  whole 
length  of  the  medulla  spinalis,  and  consist  in  a series  of  little 
depressions,  running  into  each  other  and  transmitting  the 
filaments  which  form  the  roots  of  the  spinal  nerves.  The 
posterior,  of  the  last  named  lateral  fissures,  is  deeper  than 
the  anterior,  and  penetrates  in  the  same  direction  with  the 
lateral  fissures  first  mentioned;  it  also  in  like  manner  joins 
its  fellow,  but  only  after  having  proceeded  to  within  a few 
lines  of  the  inferior  end  of  the  medulla  spinalis. 

The  substance  of  the  spinal  marrow  being  of  two  kinds, 
cineritious  and  medullary,  the  order  of  their  position  is  re- 
versed from  what  occurs  in  the  brain;  for  the  cineritious  is 
included  or  enveloped  by  the  other.  On  making  a transverse 
section  the  cineritious  will  be  found  much  less  abundant  than 
the  other,  and  consisting  of  a thin  transverse  part  in  or  near 
the  centre  of  the  medulla.  This  part  is  joined  at  either  end 
to  a portion  somewhat  crescentic,  whose  concavity  is  out- 
wards, and  the  convexity  inwards.  The  transvmrse  part 
does  not  run  into  the  middle  of  the  crescent,  but  somewhat 
anterior  to  the  middle,  so  that  the  anterior  horn  is  shorter 
than  the  other,  and  is  also  thicker  and  more  obtuse,  having 
its  end  covered  by  medullary  matter,  while  the  remainder 
is  not.  The  cineritious  or  grayish  substance  is  more  abun- 
dant at  the  lower  part  of  the  medulla  spinalis  than  it  is  above. 
In  the  foetus,  at  the  end  of  gestation,  it  predominates  below, 
occasionally  to  the  entire  exclusion  of  the  other.  The  me- 
dullary or  white  substance  is  more  abundant  laterally  than 
elsewhere,  and  has  its  two  syniinetrical  sides  joined  together 
by  a thin  lamina  at  the  bottom  of  the  anterior  and  of  the 
posterior  fissure. 


* Meckel,  Manuel  D’Anatomie. 


326 


NERVOUS  SYSTEM. 


Each  half  or  symmetrical  side  of  the  medulla  spinalis  is 
itself  divided  into  two  chords,  marked  off  from  each  other 
by  the  posterior  horn  of  the  cineritioiis  crescent,  and  by  the 
intermediate  lateral  fissure.  Of  these  chords  the  anterior 
is,  consequently,  much  the  larger;  it  is  also  longer  and 
forms  the  inferior  extremity  or  the  point  of  the  medulla  spi- 
nalis. The  posterior  chord,  though  so  much  smaller  and  nar- 
rower, than  the  anterior,  is  itself  subdivided  into  two,  by  a 
slight  but  well  marked  fissure;  of  the  two  last  chords  the  one 
next  to  the  posterior  middle  fissure  of  the  medulla  is  smaller 
than  the  other.  These  arrangements,  according  to  Meckel, 
are  much  more  obvious  in  the  early  life  of  the  human  sub- 
ject, than  afterwards,  and  are  particularly  conspicuous  in 
the  brute  creation. 

The  thin  white  laminae  by  which  the  two  sides  of  the  spi- 
nal marrow  adhere  to  each  other  at  the  bottom  of  the  mid- 
dle fissures,  are  called,  by  modern  anatomists.  Anterior  and 
Posterior  Commissures.  Their  precise  arrangement  is  not 
yet  fully  ascertained,  but  it  is  stated  by  Gall  and  Spur- 
zheim*  that  the  Anterior  Commissure  is  formed  by  trans- 
verse fibres  or  filaments,  which  adhere  to  one  another  from 
the  opposite  sides  like  a suture,  or  after  a sei’rated  fashion; 
whereas  the  Posterior  Commissure  is  formed  by  a band  of 
longitudinal  fibres.  There  is  also  another  Commissure, 
called  Middle  or  Cortical,  from  its  position  and  from  its 
being  formed  out  of  the  transverse  part  of  the  grayish  sub- 
stance. 

The  chords  which  form  each  half  of  the  medulla  are  diffe- 
rently disposed,  the  posterior  continues  on  the  side  to  which 
it  specially  belongs,  while  the  anterior  having  got  within 
the  circumference  of  the  first  cervical  vertebra  crosses  over 
to  the  opposite  side  by  decussating  with  its  fellow.  This 
decussation  occupies  the  space  of  four  or  five  lines,  and  in- 
terrupts, for  that  distance,  the  middle  fissure  on  front  of  the 
medulla.  It  is  not  effected  by  the  chords  passing  in  mass 
from  one  side  to  the  other,  but  each  chord  sends  off  four 
or  five  fasciculi,  which  are  interwoven  with  their  congeners 
like  the  fingers  of  the  two  hands  when  interlocked  oblique- 

Recherches  surle  Syst.  Nerv.  ct  snr  ce  lui  du  Cerveau.  Paris,  1809. 


SPINAL  MAKROVV. 


327 


ly.  It  is  to  be  observed  that  the  whole  mass  of  the  anterior 
chords  is  not  subjected  to  such  distribution;  for  the  fasciculi 
just  described  come  from  their  anterior  and  from  their  pos- 
terior faces,  the  middle  part  being  permitted  to  pursue  their 
course  straight  upwards.  This  decussation,  upon  which  so 
much  interesting  physiological  speculation  depends,  though 
known  for  the  last  century,  and  spoken  of  by  Mistichelll  and 
Petit,  has  been  strangely  overlooked  by  many  anatomists, 
and  is  even  positively  denied  by  some.  There  are  other 
places  where  the  fasciculi  of  the  spinal  marrow  seem  to  cross 
from  one  side  to  the  other,  but  the  fact  is  not  yet  verified. 

The  existence  of  canals  in  the  spinal  marrow  has  been 
from  time  to  time  announced;*  though  authors  differ  much 
in  the  accounts  of  their  position  and  extent.  When  such  an 
appearance  is  presented,  it  is  supposed,  by  some,  to  be  either 
the  result  of  disease  or  of  accident,  with  the  exception  of  a 
small  one  of  eight  or  nine  lines  long,  which  communicates 
at  one  end  with  a fourth  ventricle,  and  is  shut  up  at  the 
other.t 

The  Spinal  Marrow  sends  out  from  its  sides  thirty  pairs 
of  Nerves,  which,  like  the  vertebras,  are  arranged  into  cei'- 
vical,  dorsal,  or  thoracic,  lumbar,  and  sacral.  Of  these 
there  are  eight  cervical,  one  of  which,  from  its  escaping  be- 
tween the  occiput  and'  the  first  vertebra,  is  most  usually 
designated  as  suboccipital,  and,  therefore,  the  number  of 
the  cervical  nerves  is  reduced  to  the  same  with  that  of  the 
vertebrae,  to  wit,  seven.  There  are  twelve  pairs  of  dorsal 
nerves,  five  of  lumbar,  and  five  of  sacral.  Occasionally  there 
is  a sixth  sacral  nerve  on  each  side,  which  augments  the 
number  of  spinal  nerves  to  thirty -one  pairs. 

Every  spinal  nerve  is  formed  from  two  roots  on  the  same 
level,  one  before  and  the  other  behind,  and  each  root  con- 
sists in  several  fasciculi  of  nervous  matter.  The  front  root 
arises  from  the  anterior  chord  of  the  medulla  spinalis,  and 
the  other  from  the  posterior  chord.  The  posterior  root  is 
larger  than  the  anterior,  but  has  fewer  fasciculi  in  its  cora- 

* Gal],  Portal,  Morgagni. 

t Meckel,  p.  605,  vol.  II.  Bichat,  vol.  III.  p.  128. 


S28 


NERVOUS  SYSTEM. 


position,  and  is  not  so  filamentous.  The  two  roots  are  kept 
asunder  by  the  Ligamentum  Denticulatum.  The  fasciculi  of 
each  are  slightly  connected  by  a loose  delicate  cellular  sub- 
stance, and  as  they  are  about  penetrating  rhe  dura  mater,  each 
fasciculus  collects  into  a single  chord,  which  passes  the  dura 
mater  through  its  appropriate  foramen.  In  this  way  the 
anterior  and  posterior  roots  are  kept  distinct  till  they  have 
got  to  the  outside  of  the  membrane  mentioned;  but  the  fo- 
ramina through  which  they  pass  border  closely  upon  one 
another.  The  posterior  root,  then  forms  a ganglion  of  a 
round  or  oval  shape,  from  whose  external  extremity  there 
proceeds  a single  nervous  trunk,  which  is  joined  immedi- 
ately at  its  commencement  by  the  anterior  root. 

With  the  exception  of  the  ganglions  of  the  sacrum,  which 
are  in  the  spinal  cavity  of  that  bone,  these  bodies  are 
placed  in  the  intervertebral  foramina.  The  size  of  the  gan- 
glion is  not  proportionate  to  that  of  the  nerve  from  which 
it  proceeds;  for  some  of  the  dorsal  ganglions  are  the  largest, 
while  those  of  the  sacrum  are  smaller  than  any  others. 

The  two  nerves  of  the  same  pair,  though  generally  sym- 
metrical or  precisely  resembling,  are  not  invariably  so; 
sometimes  one  is  placed  higher  than  another,  and  the  num- 
ber of  tlie  fasciculi  may  be  greater  or  smaller.  The  roots 
of  the  nerves  are  much  nearer,  or  cluster  more  at  the  ex- 
tremities of  the  spinal  marrow,  than  in  its  middle.  The 
lumbar  and  sacral  nerves  are  indeed  so  close  together  and 
so  much  in  a bunch,  that  the  arrangement  is  designated  by 
the  term  Cauda  Equina. 

The  Cervical  Pairs  of  Nerves  are  nearly  horizontal  in 
their  course  from  the  medulla  spinalis  to  the  foramina  in 
the  dura  mater.  The  first  one,  or  the  sub-occipital,  is 
strictly  so;  the  others  incline  very  gradually  more  and  more 
downwards.  They  have,  therefore,  but  a very  short  pas- 
sage before  they  reach  the  intervertebral  foramina.  Their 
roots  are  so  pyramidal,  that  the  bases  nearly  touch  each 
other,  and,  for  the  most  part,  are  connected  by  an  anasto- 
mosing filament,  which  goes  from  the  upper  margin  of  the 
root  below  to  the  lower  margin  of  the  root  above.  These 


MEMBRANES  OF  THE  SPINAL  BIAEROW. 


329 


anastomoses  are  found  connecting  the  upper  with  the  lower 
fasciculi,  both  on  the  anterior  and  posterior  chords  of  the 
medulla,  but  more  uniformly  as  regards  the  latter.  Modi- 
fications of  this  arrangement,  which  it  is  unnecessary  to 
specify,  are  met  with  in  different  subjects. 

The  Dorsal,  or  Thoracic  Pairs,  are  much  inferior  in  size 
to  any  others,  except  the  inferior  sacral.  Anastomosing 
filaments  do  not  generally  prevail,  yet  they  are  found  occa- 
sionally, as  in  the  neck,  upon  the  two  or  three  upper  pairs. 
The  first  one  has  the  broad  pyramidal  or  triangular  root  of 
a cervical  nerve,  and  resembles  it  also  in  volume.  The 
second  is  the  smallest  of  any,  they  then  go  on  increasing 
in  size  to  the  lowest,  but  not  in  a uniform  gradation. 
They  are  successively  more  oblique,  and  consequently 
longer  from  their  bases  to  their  passage  through  the  dura 
mater. 

The  Lumbar  and  the  Sacral  Pairs  arise  close  upon  each 
other,  indeed  in  absolute  contact  successively,  from  the 
lower  enlargement  of  the  medulla  spinalis.  As  their  place 
of  origin  is  within  the  precincts  of  the  first  lumbar  verte- 
bra and  the  two  or  three  last  dorsal,  they  all  observe  a very 
oblique  course  in  their  descent  to  the  vertebral  foramina, 
and  the  lower  ones  are  almost  vertical.  Notwithstanding, 
they  are  in  contact  and  adhere  by  a loose  cellular  substance, 
yet  there  are  no  anastomosing  filaments  between  the  adja- 
cent roots.  From  the  sacral  ganglions  presenting  the  pe- 
culiarity of  being  situated  in  the  spinal  cavity  of  the  sa- 
crum, instead  of  in  the  foramina,  the  single  nerve  formed 
from  the  ganglion  and  the  anterior  fasciculus,  has  to  pro- 
ceed a distance  more  or  less  considerable  in  the  spinal  ca- 
vity before  it  can  escape  from  it. 

SECT.  II. MEMBRANES  OF  SPINAL  MARROW. 

Of  the  Dura  Mater  of  the  Medulla  Spinalis. 

This  membrane,  forming  the  exterior  envelope  of  the 
spinal  marrow,  extends  from  one  end  of  the  spinal  canal  to 

VoL.  II. — 42 


oJO 


NEKVOUS  SYSTEM. 


tlie  other,  being  continuous  above  with  the  dura  mater 
of  the  brain,  and  terminating  below  in  a cul-de-sac  or 
closed  extremity.  It  does  not  adhere  to  the  surface^of  the 
spinal  canal,  but  lies  loosely  attached  to  it,  with  the  excep- 
tion of  the  first  cervical  vertebra,  to  which  it  is  closely  fas- 
tened. Between  it,  and  the  ligaments  and  periosteum  on 
this  surface  of  the  bones  of  the  spine,  is  a long,  loose,  and 
spare  cellular  substance,  generally  somewhat  watery,  and 
containing  in  the  lumbar  and  sacral  regions,  a reddish  adi- 
jDOse  matter.  This  membrane  is  so  much  larger  than  the  me- 
dulla, that  it  invests  it  very  loosely  and  always  presents  a 
collapsed  appearance. 

Where  the  nerves  penetrate,  it  furnishes  to  each  one,  a 
sheath  as  far  as  the  intervertebral  foramen.  Those  sheaths 
are  longer  for  the  cauda  equina  than  elsewhere,  and,  of 
course,  observe  the  same  successive  obliquity  with  the 
nerves  to  which  they  belong.  Having  reached  the  inter- 
vertebral foramina,  they  enlarge  so  as  to  enclose  the  gan- 
glions, adhere  by  cellular  substance  to  the  contiguous  peri- 
osteum, and  are  then  insensibly  lost  in  the  tunics  of  the 
nervous  trunks.  The  internal  surface  of  the  dura  mater  is 
smooth  and  shining,  which  is  probably  owing  to  the  tunica 
arachnoideae  being  reflected  over  it.  This  membrane  has 
a fibrous  texture,  and,  with  inconsiderable  exceptions,  is 
like  that  of  the  brain. 

Of  the  Tunica  Jirachnoidea  of  the  Medulla  Spinalis. 

This  membrane  is  next  to  the  dura  mater,  and  is  easily 
distinguished  by  its  extreme  delicacy,  thinness,  and  almost 
perfect  transparency.  It  is  destitute  of  red  blood  vessels. 
It  forms,  also,  a complete  envelope  for  the  medulla  spina- 
lis, and  adheres  to  it  only  very  loosely  by  means  of  long, 
slender,  and  scattered  filaments  of  cellular  substance.  If 
the  dura  mater  be  slit  up  its  whole  length  before  and  be- 
hind, and  a blow-pipe  be  introduced  at  one  end  of  the  me- 
dulla, between  the  pia  mater  and  the  arachnoidea,  inflation 
will  cause  the  latter  to  rise,  and  to  present  itself  as  a long 


MEMBRANES  OF  THE  SPINAL  MARROW. 


331 


capacious  tube,  detaching  on  each  side  processes  which  sur- 
round the  roots  of  the  nerves.  These  processes  having 
reached  the  points  where  the. nerves  penetrate  the  dura 
mater,  are  then  reflected  upon  its  internal  face,  and  are  sup- 
posed to  give  it  the  glistening  appearance.  The  processes 
enclosing  the  fasciculi  of  the  spinal  nerves,  are  particularly 
conspicuous  about  the  Cauda  Equina. 

. Of  the  Pia  Mater  of  the  Medulla  Spinalis. 

This  third  envelope  of  the  spinal  marrow  forms  also  a 
complete  investment  of  the  latter,  and  adheres  very  closely 
to  it.  Its  external  face  is  smooth,  and  is  in  contact  with 
the  arachnoidea,  from  which  it  may  be  readily  separated  by 
inflating  the  latter.  But  from  the  middle  of  its  internal 
face  both  anteriorly  and  posteriorly,  a process  or  partition 
penetrates  into  the  middle  fissures  of  the  medulla  spinalis, 
and  reaches  to  their  bottoms.  From  these  partitions  there 
proceed  a great  number  of  small  vascular  canals,  that  pass 
in  various  directions  through  the  medulla,  and  anastomose 
freely  with  each  other.  This  arrangement  is  rendered  suf- 
ficiently obvious  by  injection,  and  then  destroying  the  me- 
dulla in  an  alkaline  solution;  or  if  the  medulla  be  hardened 
by  neutral  salts  or  acids,  it  splits  into  longitudinal  laminae, 
divisible  into  chords,  whereby  the  arrangement  is  made 
equally  manifest.  A fact  of  some  consequence  is  thus  es- 
tablished, to  wit,  the  similitude  between  the  structure  of  a 
nerve  and  of  the  medulla  spinalis. 

At  the  inferior  end  of  the  medulla  the  pia  mater  becomes 
a single  chord,  which  is  continued  among  the  cluster  of 
nerves,  to  the  lower  end  of  the  tube  formed  by  the  dura 
mater,  and  there  it  joins  with  the  latter.  As  a membrane, 
the  pia  mater  is  much  more  complete  than  the  correspond- 
ing one  of  the  brain,  has  more  strength,  but  is  not  so  vas 
cular.  Its  thickness  increases  in  its  descent.  It  is  of  a 
yellowish-white  colour.  It  seems  to  hold  the  medulla 
somewhat  in  a state  of  compression,  for  when  a puncture  is 
made  through  it,  the  medullary  substance  protrudes  like  a 


NERVOUS  SYSTEM. 


hernia.  It  goes  from  the  medulla  to  the  fasciculi  of  nerves, 
and  forms  their  neurileme  or  sheath. 

Of  the  Ligament  a Denticiila. 

These  bodies  are  narrow  semitransparent  bands,  and  very 
tbin,  which  are  placed  one  on  either  side  of  the  medulla 
spinalis,  between  the  pia  mater  and  the  tunica  arachnoidea. 
They  commence  at  the  occipital  foramen,  and  descending 
between  the  anterior  and  the  posterior  fasciculi  of  nerves, 
terminate  somewhat  above  the  inferior  extremity  of  the 
medulla. 

Each  one  is,  at  its  commencement,  in  front  of  the  acces- 
sory nerve,  and  in  descending  is  rather  nearer  to  the  pos- 
terior than  to  the  anterior  fasciculi.  By  its  internal  margin 
it  adheres  with  uniformity  to  the  pia  mater,  but  the  exter- 
nal margin  has  a very  different  arrangement;  for  it  sends  off 
at  intervals  from  twelve  to  twenty-four  serrated  or  denticu- 
lated processes,  which  for  the  most  part  are  placed  between 
the  fasciculi  of  cervical  and  of  dorsal  nerves.  The  extremi- 
ties of  these  teeth  are  small,  rounded,  and  strong,  are  sur- 
rounded by  the  arachnoidea,  and  adhere  very  forcibly  to  the 
dura  mater,  being  pointed  downwards.  The  position  and 
connexions  of  each  ligamentum  denticulatum  are  such,  as 
to  make  it  serve  as  a fastening;  which  use  is  additionally 
indicated  by  its  fibrous  texture,  and  by  the  necessity  that 
the  medulla  has  for  such  fastening,  in  consideration  of  its 
being  so  deficient  in  filling  up  the  vertebral  canal. 

It  is  taught  by  many  anatomists,  that  the  ligamenta  den- 
ticulata,  from  the  opposite  sides,  join  at  the  lower  end  of 
the  spinal  marrow  to  form  the  single  cylindrical  chord  that 
passes  thence  to  the  lower  end  of  the  spinal  cavity,  and  has 
been  described  as  an  emanation  from  the  pia  mater.  I am, 
however,  induced  to  think  with  Meckel  and  others,  that 
general  analogy  is  in  favour  of  the  latter. 


BLOOD  VESSELS  OF  THE  MED0LLA  SPINALIS. 


333 


SECT.  III. — =OF  THE  BLOOD  VESSELS  OF  THE  MEDULLA 
SPINALIS. 

The  Arteries  of  the  Spinal  Marrow  are  derived  from  the 
Vertebrals,  Intercostals,  Lumbar,  and  Sacral  Arteries. 

1.  The  Posterior  Spinal  Artery  {Jirteria  Spinalis  Pos- 
terior) is  the  lowest  branch  of  the  vertebral,  given  off  in  the 
cavity  of  the  cranium.  It  reaches,  soon  after  its  origin,  the 
posterior  face  of  the  Medulla  Spinalis,  and  runs  to  the  lower 
extremity  of  the  latter,  on  the  side  of  its  posterior  fissure. 
Its  course  is  parallel  with  its  fellow,  and  very  serpentine. 
In  its  descent  it  is  continually  re-enforced  by  the  small 
branches  which  get  into  the  spinal  cavity  through  each  of 
the  intervertebral  foramina. 

2.  The  Anterior  Spinal  Artery  {Jirteria  Spinalis  Jinte- 
rior)  arises  above  the  last  from  the  vertebral.  Shortly  after 
its  origin  it  unites  with  its  fellow  into  a common  trunk, 
which  descends  along  the  anterior  fissure  of  the  medulla 
spinalis,  but  is  subject  to  interruptions.  It  also  is  re-en- 
forced by  twigs  from  the  arteries  that  pass  into  the  spinal 
cavity  through  the  intervertebral  foramina.  In  its  whole 
course  it  sends  off  branches  from  each  side  to  the  medulla 
spinalis. 

The  Cauda  Equina  is  supplied  by  arteries  from  the  Lum- 
bar and  from  the  Sacral  arteries,  which  reach  it  through  the 
foramina,  between  the  vertebrae,  and  in  the  sacrum. 

The  Veins  of  the  Spinal  Marrow  are  very  abundant.  A 
large  one,  called  the  Sinus  ColumnaeVertebralis,  is  situated 
in  the  spinal  cavity,  on  the  posterior  face  of  the  bodies  of 
the  vertebrae,  between  their  ligamentous  covering  and  the 
dura  mater.  One  of  these  veins  exists  on  each  side  of  the 
middle  line.  They  detach  a considerable  number  of  branches, 
which  run  transversely,  and  anastomose  with  one  another 


334 


NERVOUS  SYSTEM. 


on  the  body  of  each  vertebra,  so  that  each  vertebra  has  its 
little  system  of  anastomosing  branches,  called  Circelli  Ve- 
nosi.  These  anastomoses  communicate  with  the  intercostal 
veins,  and  indeed  with  all  such  as  are  on  the  outside  of  the 
spinal  column,  by  means  of  small  branches,  that  get  out  by 
the  intervertebral  foramina.  They  receive  the  veins  from 
the  bodies  of  the  vertebrae,  and  from  the  dura  mater  of  the 
spine. 

The  two  sinuses  may  be  traced  as  low  down  as  the  infe- 
rior end  of  the  sacrum,  where  they  arise  by  small  trunks 
from  the  fatty  matter  which  surrounds  the  lower  end  of  the 
cauda  equina.  When  their  size  is  somewhat  augmented  by 
their  ascent,  tliey  communicate  by  a large  transverse  branch. 
The  superior  end  of  each  sinus  terminates  by  several  anas- 
tomoses with  the  vertebral  vein,  and  with  the  anterior  occi- 
pital sinus,  through  the  latter  of  which  its  blood  is  finally 
carried  into  the  lateral  sinus.  For  a further  account  see 
Sinus  Vertebrales. 


CHAPTER  II. 

OP  THE  ENCEPHALON,  OR  BRAIN. 

Bv  this  term  is  designated  that  section  of  the  central  por- 
tion of  the  nervous  system,  which  is  contained  within  the 
bones  of  the  cranium.  In  its  general  configuration  it  differs 
materially  from  the  medulla  spinalis  in  being  spheroidal  or 
oval.  It  is  surrounded  by  the  same  membranes;  to  wit,  the 
Dura  Mater  externally,  the  Tunica  Arachnoidea  next,  and 
the  Pia  Mater  internally. 

The  Encephalon  is  formed  by  cineritious^  and  medullary 
matter,  and  as  a mass  consists  of  four  distinct  portions. 


NERVES  OF  THE  ENCEPHALON. 


335 


The  Medulla  Oblongata,  which  is  a continuation  of  the  spi- 
nal marrow  or  its  superior  part;  the  Protuberantia  Annu- 
laris or  Pons  Varolii,  which  is  placed  at  the  upper  extre- 
mity of  the  Medulla  Oblongata;  the  Cerebrum,  which  oc- 
cupies six  or  seven-eighths  of  the  cavity  of  the  cranium; 
and  the  Cerebellum,  which  lies  upon  the  posterior  fossae  of 
the  base  of  the  cranium.  As  the  brain  is  a double  organ, 
each  of  these  parts  is  symmetrical,  or  consists  in  right  and 
left  halves  perfectly  alike. 


■SECT.  I. OP  THE  MEMBRANES,  OP  THE  BRAIN  OR 

ENCEPHALON. 

Of  the  Dura  Mater. 

This  membrane,  the  most  exterior  of  the  three  belonging 
to  the  encephalon,  lines  the  whole  internal  face  of  the  cavity 
of  the  cranium,  and  adheres  with  great  tenacity  to  its  bones, 
particularly  in  early  life,  from  which  cause  it  is  also  consi- 
dered as  an  internal  periosteum. 

Its  external  surface  has  a rough  and  unequal  appearance, 
and  adheres  much  more  strongly  to  the  bones  where  the 
sutures  exist  than  elsewhere,  owing  to  its  detaching  many 
large  filaments,  which  penetrate  into  the  sutures  and  reach 
to  the  pericranium.  To  the  surface  of  the  bones  it  adheres 
by  very  fine  filaments  of  fibres,  and  by  very  numerous  and 
small  blood  vessels  which  become  very  evident  by  the  dots 
of  blood  seen  upon  its  surface,  when  the  bones  are  torn  up 
from  it,  as  in  the  usual  manner  of  examining  the  head.  To 
the  base  of  the  cranium,  its  adhesion  is  unusually  strong, 
owing  to  the  abundance  of  the  foramina  and  fissures  there; 
to  the  margin  of  each  one  of  which  it  is  fixed  with  extreme 
compactness,  and  may  be  considered  as  continuous  with  the 
adjacent  pericranium. 

The  external  surface  is  marked  by  the  arteries  and  veins 
which  creep  and  ramify  through  it,  and  make,  as  mentioned 
elsewhere,  corresponding  furrows  in  the  bones. 


336 


NERVOUS  SYSTEM. 


The  Dura  Mater  consists  of  two  laminae,  one  within  the 
other;  they,  however,  adhere  so  closely  in  the  greater  part 
of  their  extent,  that  it  requires  the  knife,  or  strong  artificial 
force  to  separate  them.  Sometimes,  in  tearing  off  the  skull 
cap  of  a middle  aged  person,  the  external  lamina  is  brought 
away  with  the  bone. 

Several  Processes  arise  by  a duplicature  of  the  internal 
lamina  of  the  dura  mater,  and  extend  from  the  circumference 
towards  the  centre  of  the  cavity  of  the  cranium.  They  are 
as  follows: 

The  Falx  Cerebri  separates  the  hemispheres  of  the  brain, 
and  is,  consequently,  precisely  under  the  middle  line  of  the 
head.  Its  shape  is  well  indicated  by  its  name.  It  commences 
by  a small  point  from  the  middle  of  the  body  of  the  sphe- 
noid bone,  and  continues  to  arise  along  the  crista  galli,  the 
spine  and  middle  line  of  the  frontal  bone,  the  sagittal  su- 
ture, and  the  upper  limb  of  the  occipital  cross,  till  it  reaches 
the  internal  occipital  protuberance.  It  is  about  an  inch 
broad  in  front,  where  it  begins,  but  it  increases  continually 
though  gradually  in  breadth  till  its  termination,  where  it  is 
two  or  two  and  a half  inches  wide.  It  is  strongly  fastened 
along  the  crista  galli  and  at  the  foramen  coecum,  and  being 
also  fastened  behind  to  the  tentorium  (with  which  it  is  con- 
tinuous) as  well  as  along  the  intermediate  points  of  bone,  it 
is  kept  in  a state  of  strict  tension,  which  does  not  admit  of 
its  wavering  to  one  side  or  to  the  other.  Its  inferior  mar- 
gin is  very  concave,  and  goes  to  within  a small  distance  of 
the  corpus  callosum.  There  are  sometimes  considerable 
apertures  in  it,  through  which  the  flat  surfaces  of  the  he- 
mispheres come  in  contact. 

The  Tentorium  Cerebelli,  another  process  of  the  dura 
mater,  is  placed  transversely  across  the  posterior  part  of  the 
cranium,  and  separates  the  cerebellum  from  the  posterior 
lobes  of  the  cerebrum.  It  is  continuous  with  the  posterior 
end  of  the  falx  major,  whereby  these  two  processes  ex- 


MEMBRANES  OF  THE  ENCEPHALON. 


337 


ercise  a mutual  tension.  The  tentorium  is  therefore  kept 
■convex  above  and  concave  below. 

Its  form  is  crescentic;  its  outer  circumference  is  extended 
along  the  horizontal  limbs  of  the  occipital  cross,  and  along 
the  superior  corner  or  margin  of  the  petrous  bones  to  the 
posterior  clinoid  process.  The  internal  circumference  is 
much  smaller  and  unattached,  and  being  placed  immediate- 
ly behind  the  sella  turcica,  it  leaves  an  opening  (the  Fora- 
men Ovale)  which  is  of  nearly  the  same  size  with,  and  occu- 
pied by  the  tuber  annulare.  The  anterior  extremities  of  the 
crescent  are  continued  from  the  posterior  clinoid  process  to 
the  anterior  on  each  side,  so  that  a deep  depression  is  formed 
for  lodging  the  pituitary  gland. 

The  Falx  Cerebelli  is  a small  triangular  process  of  the 
dura  mater,  which  extends  in  the  middle  line  from  the  un- 
der surface  of  the  tentorium  to  the  posterior  margin  of  the 
occipital  foramen.  Its  base  is  above  and  its  point  below; 
the  latter  terminates  by  a small  bifurcation.  It  adheres  by 
its  posterior  margin  to  the  middle  inferior  limb  of  the  oc- 
cipital cross;  the  anterior  margin  is  free,  and  serves  to  se- 
parate the  two  hemispheres  of  the  cerebellum. 

The  Dura  Mater  is  essentially  fibrous,  as  is  sufficiently 
evident  at  whatever  point  it  may  be  examined.  These 
fibres  have  no  settled  course,  but  cross  each  other  in  every 
direction.  It  is  white,  sufficiently  transparent  for  the  ves- 
sels of  the  pia  mater  to  be  imperfectly  seen  through  it,  and 
almost  inelastic.  Its  internal  face  is  smooth  and  polished, 
and  is  presumed  to  be  covered  or  lined  by  the  tunica  arach- 
noidea,  the  halitus  from  which  gives  it  a slippery  feel.  It 
is  insensible  to  common  excitants,  such  as  cutting,  or  even 
cauterizing  it;  from  which  circumstance,  together  with  the 
common  inability  of  anatomists  to  trace  nerves  into  its 
structure,  it  is  supposed,  by  many,  to  be  entirely  destitute 
of  them.  The  venerable  Chaussier,  however,  takes  a diffe- 
rent position  in  regard  to  these  points,  and  says,  that  it  has 
sensibility,  and  that  though  none  of  the  cerebral  nerves  can 

VoL.  II. — 43 


J3S  MERVOUS  SYSTEM. 

be  traced  into  it,  yet  by  attentive  examination  it  is  found, 
that  filaments  from  the  sympathetic  nerve  follow  the  rami- 
fications of  its  middle  or  great  artery.* 

It  is  well  supplied  with  blood  vessels,  both  arteries  and 
veins.  The  former  are  derived  principally  from  the  branch  of 
the  internal  maxillary  of  either  side,  which  gets  into  the  cra- 
nium through  the  foramen  spinale.  There  are  branches  also 
from  the  sethmoidal,  the  inferior  pharyngeal,  and  the  ver- 
tebral. The  branch  of  the  internal  maxillary  divides  into 
two,  of  which  the  anterior  being  the  more  considerable, 
gains  the  anterior  and  inferior  angle  of  the  parietal  bone; 
but  the  other  is  directed  backwards  to  the  squamous  por- 
tion of  the  temporal.  Each  of  these  branches  is  subdivided 
into  a considerable  number  of  smaller  ones,  which  for  the 
most  part  incline  backwards.  Their  capillary  terminations 
are  supposed  by  Bichat  to  be  in  small  number  comparative- 
ly, and  to  be  limited  principally  to  those  of  nutrition. 

Some  of  the  veins  accompany  the  arteries,  as  in  other 
parts  of  the  body,  and  empty  into  the  sinuses  about  the  base 
of  the  cranium.  In  the  case  of  both  arteries  and  veins, 
there  is,  however,  a very  considerable  anastomosis  with  the 
blood  vessels  of  the  diploic  structure  of  the  cranium,  and 
with  those  of  its  integuments. 

Of  the  Sinuses  of  the  Dura  Mater. — The  sinuses  are 
large  cavities  placed  between  the  two  laminae  of  the  dura 
mater,  and  receive  the  blood  from  the  veins  of  the  pia  ma- 
ter They  are  formed  by  the  separation  of  these  laminae, , 
and  are  lined  by  a membrane  corresponding  with  the  inter- 
nal coat  of  the  veins. 

1.  The  Sinus  Longitudinalis  Superior  extends  along  the 
whole  base  of  the  falx  cerebri,  from  the  ethmoid  bone  to 
the  tentorium,  where  it  terminates  in  the  lateral  sinuses. 
It  begins  at  the  foramen  ccecum  in  a small  pointed  manner, 
and  according  to  some  anatomists  by  a small  vein,  which 


* Exposition  de  L’Encephale,  p.  29. 


MEMBRANES  OF  THE  ENCEPHALON. 


339 


passes  from  the  nose  through  this  foramen;  it  is  successive- 
ly increased  in  size  from  before  backwards,  and  is  of  a pris- 
matic shape.  One  side  of  the  prism  is  upwards,  and  of 
course  is  formed  by  the  external  lamina  of  the  dura  mater; 
while  the  other  two  parietes  are  lateral,  and  are  formed  by 
the  cTuplicature  of  the  internal  lamina.  Its  cavity  presents 
a number  of  small  cords,  round  or  flattened,  passing  from 
one  side  to  the  other;  they  are  called  Chordae  Willisii  or 
Trabeculae,  and  prevail  principally  at  its  back  part. 

The  longitudinal  sinus  receives  on  each  side  from  ten  to 
twelve  large  veins,  which  bring  the  blood  from  the  pia  ma- 
ter. Those  from  the  convex  surface  of  the  brain  are  joined 
just  before  entering  the  sinus  by  such  as  belong  to  the  flat 
side  of  the  hemispheres.  These  veins  enter  the  sinus,  for 
the  most  part,  obliquely  forwards,  or  in  a manner  opposed 
to  its  circulation.  The  most  posterior  ones  previously  glide 
eight  or  ten  lines  between  the  laminae  of  the  dura  mater, 
and  are  somewhat  tortuous;  they  are  also  furnished  with 
valves,  which  circumstance,  besides  their  oblique  entrance 
into  the  sinus,  is  a provision  against  their  being  filled  by 
the  regurgitating  blood.  This  sinus  also  receives  several 
veins  from  the  bones,  and  some  from  the  scalp,  which  tra- 
verse the  bones  at  difierent  places;  among  the  largest  of 
them  are  those  that  come  through  the  parietal  foramina. 
The  dura  mater  itself  sends  some  of  its  veins  into  this 
sinus. 

In  the  longitudinal  sinus,  towards  its  posterior  part,  are 
found  a considerable  but  variable  number  of  small  granular 
bodies;  some  in  clusters,  others  insulated;  and  from  the 
size  of  a pin’s  head  to  a line  or  more  in  diameter.  They 
are  the  Glandulae  Pacchioni;  they  have  no  excretory  ducts 
that  have  been  discovered,  and  it  is  entirely  uncertain  whe- 
ther any,  specific  fluid  is  secreted  from  them.  These  bodies 
are  also  to  be  found  on  the  surface  of  the  dura  mater  near 
the  sinus;  some  of  them  indeed  make  foramina  through  the 
dura  mater,  and  corresponding  depressions  in  the  skull. 
One  on  each  side,  larger  than  usual  and  near  the  parietal  fo- 
ramen, is  remarkable  for  this. 


340 


NERVOUS  SYSTE5X. 


2.  The  Sinus  Laterales,  one  on  each  side,  are  situated  in 
the  base  of  the  tentorium  and  follow  its  course  along  the 
grooves  ,of  the  occipital  and  temporal  bones.  They  then 
leave  the  tentorium  and  go  along  the  groove  in  the  mastoid 
portion  of  each  temporal  bone  to  reach  the  posterior  fora- 
men lacerum,  where  they  terminate  in  the  internal  jugular 
veins.  Their  shape  is  ovoidal  instead  of  prismatic,  as  the 
longitudinal  sinus  is;  they  are  also  larger  than  it. 

The  sinus  of  the  right  side  is  very  frequently  larger  than 
that  of  the  left,  and  seems  to  be  more  a continuation  of  the 
superior  longitudinal  sinus.  In  some  rare  cases  one  of 
these  sinuses  is  deficient.  The  lateral  and  inferior  veins 
of  the  cerebrum,  and  the  inferior  veins  of  the  cerebellum, 
run  into  the  lateral  sinuses. 

3.  The  Sinus  Longitudinalis  Inferior  is  situated  in  the 
falx  cerebri  just  above  its  concave  edge.  It  is  much  smaller 
than  the  superior,  and  terminates  behind  in  the  sinus  quar- 
tos. It  receives  the  veins  of  the  falx,  and  sometimes  a few 
from  the  corresponding  parts  of  the  hemispheres. 

4.  The  Sinus  Quartus,  or  Rectus,  is  situated  in  the  ten- 
torium, where  the  latter  is  joined  by  the  falx  major  or  cere- 
bri. It  is  triangular  or  prismatic,  and  runs  from  the  ante- 
rior margin  of  the  tentorium  to  the  posterior,  where  it 
terminates  in  the  extremity  of  the  longitudinal  sinus.  The 
general  union  which  is  there  found  between  the  longitudi- 
nal, the  fourth-,  and  the  lateral  sinuses,  constitutes  the  Tor- 
cular  Hierophili. 

The  anterior  extremity  of  the  fourth  sinus,  besides  re- 
ceiving the  inferior  longitudinal,  is  joined  by  the  Vena 
Galeni,  a single  trunk,  formed  by  the  junction  of  the  two 
veins  of  the  middle  of  the  velum  interpositum,  and  extend- 
ing from  the  posterior  margin  of  the  fornix  to  the  beginning 
of  the  fourth  sinus.  The  latter  in  its  course  also  receives 
the  superior  veins  of  the  cerebellum,  with  the  exception  of 
the  most  anterior  ones,  which  terminate  in  the  Vena  Ga- 
leni. 


MEMBRANES  OE  THE  ENCEPHALON. 


341 


5.  The  Sinus  Petrosi  are  small  cylindrical  cavities,  and 
are  so  called  from  being  situated  on  the  petrous  bone. 
There  are  two  on  each  side;  one  above  and  the  other  be- 
low. The  former  is  the  Superior,  and  runs  from  the  ca- 
vernous sinus  along  the  superior  margin  of  the  petrous  bone 
to  join  the  transverse  sinus,  where  the  latter  quits  the  ten- 
torium to  descend  towards  the  base  of  the  cranium.  The 
other  Petrous  Sinus  is  the  Inferior.  It  is  larger  than  the 
superior,  and  arises,  also,  from  the  cavernous  sinus  by  its 
posterior  margin.  It  then  runs  along  the  fissure  between 
the  occipital  and  the  petrous  bone,  leaving  its  mark  on  the 
margin  of  these  bones,  but  principally  on  the  former,  and 
then  terminates  in  the  lateral  sinus  just  above  the  posterior 
foramen  lacerum. 

6.  The  Sinus  Cavernosi,  one  on  each  side,  are  also 
formed  by  a separation  of  the  two  laminm  of  the  dura  mater, 
though  their  shape  is  so  different  from  that  of  the  others. 
They  are  situated  at  the  sides  of  the  sella  turcica,  and  on 
the  body  of  the  sphenoid  bone.  Their  cavity  is  very  irre- 
gular, and  is  furnished  with  a number  of  filaments,  which 
cross  in  every  direction,  and  give  it  a cellular  arrangement. 
The  internal  carotid  artery  and  the  sixth  nerve  traverse  it, 
but  are  protected  by  its  lining  membrane  being  reflected 
over  them. 

The  cavernous  sinus  anastomoses  in  front  with  the  circu- 
lar sinus,  and  behind  with  the  two  petrous  sinuses  and  the 
anterior  occipital.  It  receives,  in  front,  the  ophthalmic 
veins;  from  above,  the  anterior  and  inferior  cerebral  veins: 
and  on  the  sides,  some  veins  from  the  dura  mater. 

7.  The  Sinus  Circularis  is  placed  in  the  sella  turcica,  and 
surrounds  the  pituitary  gland.  It  is  a small  cavity  which 
receives  the  veins  of  this  gland,  and,  as  just  mentioned, 
communicates  with  the  cavernous  sinus. 

S.  In  the  posterior  part  of  the  base  of  the  cranium,  there 
are  also  some  other  sinuses  called,  from  their  position,  Oc- 
cipital. One  of  these  is  upon  the  basilar  process  of  the  os 


NERVOUS  SYSTEM. 


34i} 

occipitis,  and  extends  itself  directly  across  the  bone,  from 
the  hind  part  of  one  cavernous  sinus  to  the  corresponding 
point  of  the  other;  and  is,  therefore,  a means  of  communi- 
cation between  these  two  cavities.  Another  of  these  sinuses 
extends  from  the  region  of  the  torcular  hierophili,  or  the 
upper  extremity  of  a lateral  sinus,  along  the  base  of  the 
falx  cerebelli  to  the  posterior  margin  of  the  occipital  fora- 
men, where  it  bifurcates  and  then  goes  along  the  margin  of 
this  foramen  to  discharge  itself  into  the  lateral  sinus  at  the 
posterior  foramen  lacerum. 

The  smaller  sinuses  about  the  base  of  the  cranium,  besides 
the  outlets  mentioned,  have  collateral  ones,  which  pass  at 
different  places  through  the  base  of  the  cranium,  and  run 
into  the  branches  of  the  internal  jugular  vein.  These  com- 
munications were  known  to  Santorini,  and  are  called  his 
Emissaries. 

Of  the  Tunica  Jirachnoidea. 

This  membrane  is  the  second  of  the  envelopes  of  the 
brain,  and  is  spread  over  the  surface  of  the  pia  mater,  ad- 
hering to  it  closely  in  the  greater  part  of  its  extent.  It  is 
so  diaphanous  and  thin,  as  its  name  implies,  that  it  is  distin- 
guished with  some  difficulty,  wherever  it  adheres  to  the  pia 
mater;  which  it  does  all  over,  with  the  exception  of  some 
few  places  on  the  basis  of  the  brain,  as,  for  example,  just 
in  front  of  the  tuber  annulare,  and  behind  the  medulla  ob- 
longata. There  this  membrane  may  be  seen  stretched  from 
one  prominence  to  another,  and  separated  considerably  from 
the  pia  mater.  It  does  not  follow  the  anfractuosities  of  the 
brain,  but  goes  directly  across  them,  from  the  ridge  of  one 
convolution  to  that  of  the  adjacent,  so  that  it  is  entirely 
. smooth  and  uniform  in  its  distribution.  Notwithstanding 
the  general  closeness  of  its  connexion  vyith  the  pia  mater, 
it  may  yet  be  separated  from  it  by  careful  dissection,  by 
slight  maceration,  or  by  the  use  of  the  blow-pipe;, dropsical 
effusions  frequently  make  out  the  distinction  between  the 
two  membranes;  also  the  deposite  of  coagulating  lymph. 


MEMBRANES  OF  THE  ENCEPHALON. 


o4o 


• Considering  this  membrane  as  a single  layer,  we  have  to 
speak  of  the  dura  mater  as  lying  loosely  upon  it.  But  the 
authority  of  Bichat,  sanctioned  by  the  testimony  of  many 
other  anatomists,  has  assigned  to  it  a much  more  considera- 
ble extent.  For  it  seems  to  be  well  ascertained,  both  by 
analogy  and  by  observation,  that  it  is  a sac;  which,  besides 
covering  the  external  surface  of  the  pia  mater,  is  reflected 
over  the  internal  surface  of  the  dura  mater,  and  gives  to  the 
latter  its  smooth  shining  appearance.  This  lining  is  on  the 
same  principle  that  the  serous  lamina  of  the  pericardium 
lines  its  fibrous  lamina,  or  that  the  synovial  membrane  lines 
the  ligamentous  attachments  of  an  articulation.  In  the  early 
periods  of  life,  it  may  be  separated  from  the  dura  mater  by 
dissection.  Vicq.  D’Azyr  has  related  a case  in  which  it  was 
detached  by  a collection  of  pus.  Its  places  of  reflection  to 
the  dura  mater  are  on  the  basis  of  the  cranium,  where  the 
blood  vessels  and  nerves  pass  into  the  sheaths  formed  by 
the  dura  mater,  and  along  the  blood  vessels  entering  into 
the  sinuses. 

The  tunica  arachnoidea  passes  into  the  ventricles  of  the 
brain  by  the  same  apertures  that  the  pia  mater  does,  but  it 
is  much  less  manifest  there  than  elsewhere. 

The  texture  of  this  membrane  is  exceedingly  delicate  and 
fine.  It  is  always  found,  in  health,  in  a transparent  state, 
and  is  furnished  with  neither  red  blood  vessels  nor  nerves. 
It  secretes  a sort  of  halitus,  or  synovia,  which  facilitates 
the  motions  of  the  brain,  and  prevents  it  from  adhering. 
Occasionally,  this  secretion  is  so  much  augmented  as  to  con- 
stitute a genuine  dropsy. 

Of  the  Pia  Mater. 

The  Pia  Mater,  or  Tunica  Cerebri  Vasculosa,  is  in  con- 
tact with  the  substance  of  the  brain.  It  also  is  extremely 
delicate,  but,  unlike  the  last,  is  furnished  with  an  immense 
number  of  blood  vessels  which  go  to  or  return  from  the 
brain,  and  are,  in  most  subjects,  so  abundant  that  they  give 
a florid  ap*pearance,  at  a little  distance,  to  the  whole  mem- 
brane. Its  external  face  appears  entirely  smooth,  owing  to 


344 


NERVOUS  SYSTEM.  ' 


its  being  covered,  and  its  processes  cemented  together  by 
the  tunica  arachnoidea;  but  its  internal  face  exhibits  these 
processes  as  following  precisely  t]ie  anfractuosities  of  the 
brain;  consequentl)’^  it  is  very  unequal. 

The  pia  mater  presents,  along  the  course  of  the  longitudi- 
nal sinus,  an  abundance  of  those  small  graniform  bodies', 
existing  also  in  this  sinus,  and  called  Glandulse  Pacchioni. 
They  beset  the  veins  as  they  enter  into  the  longitudinal 
sinus,  and  even  follow  them  there,  so  that  there  is  a chain 
of  them  from  the  surface  of  the  pia  mater  into  the  sinus. 
They  are  frequently  so  abundant  on  the  superior  part  of  the 
hemispheres,  near  the  great  fissure,  that  they  cause  the  dura 
and  pia  mater  to  adhere,  as  if  from  inflammation.  It  is  the 
larger  of  this  kind  which  frequently  produce  an  absorption 
of  the  dura  mater,  and  of  the  internal  table  -of  the  skull. 
These  bodies  are  also  found,  along  with  the  pia  mater,  in 
the  ventricles  of  the  brain,  as  at  the  external  margin  of  the 
plexus  choroides,  around  the  pineal  gland,  and  at  the  bot- 
tom of  the  fourth  ventricle. 

The  Glandulse  Pacchioni,  wherever  found,  present  a si- 
milar appearance  and  structure;  varying  much  in  size,  they 
are  generally  in  clusters,  which  repose  on  common  bases. 
Anatomists  differ  much  in  their  opinion  concerning  them. 
Bichat  acknowledges  his  complete  ignorance  on  the  subject; 
Poi'tal  says  that  they  are  only  congeries  of  vessels  or  of  cel- 
lular bodies  filled  with  fat.  Meckel  states,  that  as  they  are 
found  especially  in  the  latter  periods  of  life,  and  never  be- 
fore birth;  as  they  never  exist  in  very  great  abundance, 
except  in  persons  who  have  often  experienced  diseases  of 
the  head;  and  are  not  observed  in  any  animal:  that  we  are- 
forced  to  consider  them  as  morbific  productions,  and  not  as 
Pacchioni  conceived,  glands  whose  excretory  ducts  opened 
into  the  ventricles  of  the  brain. 

The  Pia  Mater  covers  the  upper  surface  of  the  cerebrum 
with  such  uniformity  as  not  to  require  a detailed  descrip- 
tion of  it;  where  it  sinks  into  the  great  fissure  of  the  hemi- 
spheres; it  adheres  from  the  two  sides  just  above  the  corpus 


MEMBRANES  OF  THE  ENCEPHALON. 


345 


callosum.  On  the  basis  of  the  brain,  it  penetrates  deeply 
into  the  anterior  fissure  or  the  Fissura  Sylvii;  is  reflected 
over  the  inequalities,  but  never  in  such  a way  as  to  leave 
them;  and  closes  up  the  bottom  of  the  third  and  of  the  fourth 
ventricle. 

The  distribution  of  the  pia  mater,  over  the  ventricles  of 
the  brain,  is  more  complicated  than  that  over  its  periphery, 
and  it  may  be  remarked,  that  this  portion  is  called,  by  some 
anatomists,  the  Internal  Pia  Mater;  that  its  texture  is  much 
more  delicate,  and  net-like,  and  that  it  adheres  more  closely 
to  the  subjacent  parts.  Being  extended  from  the  superior 
surface  of  the  cerebellum  and  of  the  tuber  annulare,  it  en- 
ters into  the  third  ventricle,  under  the  posterior  margin  of 
the  fornix,  by  the  large  transverse  fissure  between  the  latter 
and  the  tubercula  quadrigeinina.  By  its  course  between  the 
fornix  and  thalami,  it  constitutes  the  Velum  Interpositum, 
or  the  Tela  Choroidea  of  Vicq.  D’Azyr.  The  pia  mater  is 
also  introduced  into  the  inferior  cornu  of  the  lateral  ventri- 
cles along  the  internal  margin  of  the  hippocampus  major,  at 
the  side  of  the  pons  varolii;  and  into  the  fourth  ventricle 
from  its  bottom  part.  . 

The  several  plexuses  of  vessels  found  in  the  ventricles  of 
the  brain  have  for  their  basis  the  pia  mater;  which  is  arranged 
into  a great  number  of  folds,  some  of  them  being  longitudi- 
nal and  others  crossed.  Their  formation,  according  to  the 
new  views  which  have  been  taken  of  the  development  and 
growth  of  the  brain,  by  Tiedemann,  depends  upon  the  in- 
ternal membrane  of  the  brain  contracting  itself  as  it  finishes 
the  deposite  of  medullary  matter  called  Centrum  Ovale.  The 
vessels  of  the  plexuses  are  the  arteries,  which  are  spent  upon 
the  surface  of  the  ventricles,  and  the  veins  derived  from  the 
same;  the  latter  are  much  more  numerous  than  the  first. 

Of  the  Structure  of  the  Pia  Mater. — The  pia  mater  is 
commonly  spoken  of  as  a complete  membrane,  yet  its  struc- 
ture is  different  from  that  of  membranes  generally,  inasmuch 
as  it  is  a net-work,  the  meshes  of  which  are  formed  by  ar- 
teides  and  veins,  and  the  interstices  filled  up  by  a loose, 
VoL.  II. — 44 


NERVOUS  SYSTEjr. 


3‘IG 

weak,  cellular  substance.  Bichat  has  very  justly  observed, 
that  the  union  with  the  tunica  arachnoidea  is  solely  on  the 
part  of  this  cellular  substance;  whereas  the  union  with  the 
cerebrum  is  confined  to  the  vessels,  which  are  extremely 
numerous  and  very  small  before  they  penetrate  it,  and  ap- 
pear as  bloody  points  when  we  cut  into  the  substance  of  the 
brain.  The  principal  arterial  trunks  of  the  pia  mater  are  at 
the  basis  of  the  brain;  these  trunks  divide  into  smaller 
branches,  in  the  anfractuosities  and  fissures.  The  primary 
divisions  again  divide  and  subdivide  into  tubes  not  much 
exceeding  the  size  of  capillary  vessels.  In  this  last  state 
they  enter  the  brain,  and  may  be  seen  very  readily,  either 
by  a fihe  injection  or  by  tearing  up  the  pia  mater. 

. SECT.  II. OP  THE  MEDULLA  OBLONGATA. 

According  to  the  usage  of  the  best  authorities  of  the  pre- 
sent day,  who  follow  in  the  description  of  the  central  parts 
of  the  nervous  system,  the  order  of  their  development  in  the 
human  subject,  and  also  of  their  appearance  in  animals;  I 
shall  describe  the  encephalon  from  below  upwards  instead 
of  from  above  downwards.  The  preference  thus  shown  is, 
perhaps,  principally  serviceable  in  fixing  upon  the  mind 
the  order  of  growth  and  appearance,  which  according  to 
well  established  experiments  are  exactly  in  the  order  of 
importance  to  life. 

The  Medulla  Oblongata,  also  called  Bulbus  Rachidicus, 
extends  from  the  superior  margin  of  the  first  cervical  ver- 
tebra to  the  middle  of  the  basilar  process  of  the  os  occipi- 
tis.  It  becomes  gradually  larger  as  it  ascends,  and  is  about 
an  inch  in  length,  and  eight  lines  wide  at  its  base.  It  is 
by  no  means  so  cylindroid  as  the  medulla  spinalis,  but  pre- 
sents several  risings  and  depressions  on  its  surface. 

The  under  surface  of  the  Medulla  Oblongata  is  divided 
longitudinally  by  the  middle  fissure,  a continuation  of  that 
on  the  front  of  the  Medulla  Spinalis.  The  fissure  is  two 
or  three  lines  deep,  which  is  rendered  manifest  by  removing 
the  pia  mater.  On  either  side  of  it  is  an  oblong  body  called 


THE  MEDULLA  OBLONGATA. 


347 


Corpus  Pyramidale,  which  is  a continuation  of  the  chords 
that  decussate  from  the  opposite  sides  of  the  spinal  marrow. 
These  bodies  occupy  the  whole  length  of  the  Medulla  Ob- 
longata, increase  in  breadth  as  well  as  in  elevation  during 
their  ascent,  and  are,  lastly,  somewhat  constricted  or  dimi- 
nished abruptly,  where  they  join  the  Protuberantia  Annu- 
laris or  Cerebralis.  Precisely  at  the  latter  point,  between 
their  bases,  is  a deep  triangular  pit,  into  which  penetrates 
the  pia  mater.  J.  F.  Meckel  says,  that  they  are  united  at 
their  lower  extremities  by  a small  transverse  medullary 
Commissure,  of  a line  and  a half  in  breadth.  This  junction 
is  above  the  decussation  of  the  chords  from  which  the  Cor- 
pora Pyramidalia  arise. 

The  Eminentiae  Olivares  are  two  bodies;  one  on  either 
side,  at  the  external  margin  of  the  pyramidale.  They  are 
about  seven  lines  long;  two  and  a half  wide,  and  are  ele- 
vated to  the  height  of  one  line.  The  elevation  ceases  some- 
what short  of  the  annular  protuberance,  but  their  interior 
structure  is  continued  into  the  latter,  and  may  be  traced 
into  the  thalamus  nervi  optici. 

Like  the  pyramidalia,  those  bodies  are  medullary  exter- 
nally; but  within  there  is  a nucleus  of  cineritious  matter 
called,  from  the  irregularities  of  its  margin.  Corpus  Fim- 
briatum,  and  which  encloses  some  medullary  matter.  The 
corpus  fimbriatum  is  open  at  the  inner  circumference,  and 
has  the  medullary  matter  which  it  contains  continuous  there 
with  the  substance  of  the  corpus  pyramidale.  Below,  its 
circumference  is  continuous  with  the  cineritious  matter  of 
the  medulla  spinalis.  In  the  slight  depressions  between 
the  corpora  pyramidalia  and  the  olivaria,  are  the  I'oots  of  the 
hypoglossal  nerves. 

The  Corpora  Restiformia,  one  on  either  side,  are  placed 
at  the  lateral  posterior  margins  of  the  medulla  oblongata, 
just  posterior  to  the  olivaria;  and  are  readily  brought  into 
view  by  elevating  the  contiguous  part  of  the  cerebellum. 
They  are  elliptical  risings  of  an  inch  in  length;  their  lower 


NEKVOUS  SYSTEM. 


J4S 

extremities  are  in  contact,  and  project  where  they  begin  to 
arise  from  the  borders  of  the  posterior  fissure  of  the  me- 
dulla oblongata;  they  then  diverge,  and  advance  forwards 
and  upwards  to  terminate  above  in  the  cerebellum. 

The  corpus  restiforme  is  formed  of  medullary  matter, 
and  is  a continuation  of  the  posterior  cord  of  the  medulla 
spinalis.  From  its  superior  posterior  margin  a thin  me- 
dullary lamina  of  about  three  lines  square  arises,  and  being 
sustained  by  the  pia  mater,  advances  to  meet  its  fellow,  but 
does  not  absolutely  touch  it*  From  the  anterior  margin 
of  each  corpus  restiforme  there  departs  a second  process  of 
medullary  matter,  larger  and  more  thick  than  the  preceding, 
and  being  covered  by  the  roots  of  the  pneumogastric  and 
glosso-pharyngeal  nerves,  adheres  to  the  plexus  Choroides 
of  the  fourth  ventricle. 

The  superior  face  of  the  medulla  oblongata  is  excavated 
between  the  corpora  restiformia,  in  such  a way  as  to  present 
the  outline  of  a writing  pen,  and  is  therefore  called  Cala- 
mus Scriptorius;  which  forms  a considerable  part  of  the 
floor  of  the  fourth  ventricle  of  the  Brain,  or  the  sinus 
rhomboideus.  The  fissure,  in  its  middle,  corresponds  with 
the  slit  of  a pen,  the  nib  being  downwards;  and  the  fissure 
extends  from  the  posterior  fissure  of  the  medulla  spinalis 
the  whole  length  of  the  medulla  oblongata. 

■ The  calamus  scriptorius  is  marked  by  several  streaks  of 
medullary  matter,  which  extend  themselves  transversely 
with  a very  slight  degree  of  obliquity  upwards,  and  reach 
the  external  margin  of  the  corpus  restiforme  of  the  corres- 
ponding side.  These  medullary  striae  present  some  varie- 
ties in  regard  to  their  volume,  number,  and  arrangement. 
Sometimes  they  are  slightly  elevated  narrow  lines,  which 
are  perfectly  distinct  from  each  other,  and  from  one  to 
fourteen  in  number.  On  other  occasions  their  volume  is 
greater,  but  they  are  not  so  numerous.  They  generally  ex- 
tend, either  one  or  all,  from  the  middle  fissure  to  the  com- 
mencement of  the  auditory  nerve,  and  are  thereby  a part 


Called  Pons  Sinus  Rhomboidei  by  J.  F.  Meckel. 


THE  MEDULLA  OBLOX&ATA. 


349 


of  its  origin.  Sometimes  the  anterior  ones  are  directed  to- 
wards the  origin  of  the  trigeminus  nerve,  but  their  union 
with  it  is  not  yet  ascertained;  the  posterior  ones  are  some- 
times blended  with  the  radical  filaments  of  the  pneumogas- 
tric  nerve.  The  strias  themselves,  are  sometimes  interwo- 
ven or  blended,  and  pass  the  boundary  of  the  middle  fissure 
to  join  with  those  of  the  other  side.  Their  roots  may  be 
traced  occasionally  along  the  middle  fissure,  almost  to  the 
front  or  under  surface  of  the  medulla  oblongata.  Meckel, 
whose  observations  on  this  subject  are  highly  interesting, 
is  disposed  to  consider  the  striae  not  only  as  forming  the 
roots  of  the  auditory  nerve,  but  as  also  related  closely  to 
the  trigeminus  and  to  the  pneumogastric. 

On  this  surface  also  of  the  fourth  ventricle,  or  sinus 
rhomboideus,  but  in  advance  of  the  preceding  striae,  there 
is  another  on  each  side  still  larger,  which  may  be  distin- 
guished by  its  always  beginning  at  some  distance  from  the 
middle  fissure.  Its  direction  is  transverse,  and  it  passes 
just  above  the  anterior  extremity  of  the  corpus  restiforme, 
to  run  into,  or  to  assist  in  forming,  the  root  of  the  auditory 
nerve.  Its  existence  is  much  more  constant  than  that  of 
the  others.  It  is  considered  as  an  assistant  ganglion  to  the 
auditory  nerve,  and  in  cases  of  deafness  has  been  deficient. 
Being  principally  cineritious,  it  is  called  Fasciola  Cinerea. 

In  tracing  the  continuation  of  the  structure  of  the  me- 
dulla spinalis,  into  that  of  the  medulla  oblongata,  we  find 
that  each  of  the  anterior  cords  of  the  medulla  spinalis  di- 
vides into  an  anterior,  and  into  a posterior  fasciculus;  the 
first  is  the  smaller,  crosses  the  middle  fissure,  at  the  decussa- 
tion of  Mistichelli,  and  continuing  its  course  upwards,  forms 
the  corpus  pyramidale;  while  the  larger  ascends  behind  the 
eminentia  olivaris,  and  forms  the  floor  of  the  sinus  rhom- 
boideus. There  is  a third  fasciculus  of  white  matter  be- 
tween the  other  two,  into  which  the  anterior  column  of  the 
medulla  spinalis  is  divided.  It  is  described  by  Rosenthal, 
who  says,  that  it  touches  the  eminentia  olivaris,  surrounds 
it,  and  after  having  traversed  the  annular  protuberance,  ter- 
minates in  the  tubercula  quadrigemina. 


350 


NERVOUS  SVSTEM. 


The  posterior  cords  of  the  spinal  marrow,  being  conti- 
nued into  the  corpora  restiformia,  become  still  more  evi- 
dently divided  into  two  fasciculi,  from  an  increase  of  their 
volume,  than  they  weie  in  the  vertebral  canal.  The 
internal  of  these  fasciculi  stops  by  a pointed  termination 
near  the  borders  of  the  sinus  rhomboideus;  while  the  ex- 
ternal is  continued  on  towards  the  cerebellum;  through  the 
annular  protuberance. 


SECT  ni. — PROTUBERANTIA  ANNULARIS. 

The  Annular  Protuberance  {Protuhe,rantia  Annularis, 
Nodus  Cerebri,  Pons  Varolii)  is  the  large  projecting 
body,  placed  near  the  centre  of  the  base  of  the  encephalon, 
at  the  top  of  the  Medulla  Oblongata,  and  upon  the  junction 
of  the  body  of  the  sphenoid  bone  with  the  basilar  process 
of  the  os  occipitis.  It  is  convex,  and  about  an  inch  in  di- 
ameter, its  transverse  measurement  being  a line  or  two 
larger  than  the  other.  It  is  divided  by  a superficial  fossa 
into  two  symmetrical  halves,  right  and  left. 

When  the  pia  mater  is  removed  from  the  Protuberantia 
Annularis,  the  under  surface  of  the  latter  is  seen  to  be 
formed  by  transverse  medullary  fibres  which  come  from 
the  crura  cerebelli.  When  these,  which  are  commonly 
one  or  two  lines  in  depth,  are  removed  by  scraping  or  cut- 
ting, a cineritious  matter  is  exposed,  which  is  traversed  by 
numerous  layers  of  medullary  matter  also  going  in  a trans- 
verse direction.  About  two  lines  deep  from  the  surface  of 
the  protuberance,  near  the  middle  of  each  of  its  halves, 
are  found  some  longitudinal  medullary  fibres  connected 
with  cineritious  matter,  and  which  may  be  fairly  traced  as 
a continuation  of  the  fibrous  structure  of  the  pyramids. 
These  fasciculi  passing  on  through  the  protuberance,  are 
continued  so  as  to  form  the  under  surface  of  the  crura  of 
the  cerebrum. 

Lying  still  deeper  than  the  medullary  fibres  alluded  to, 
there  is  an  accumulation  of  cineritious  matter,  intermixed 


THE  CEREBELLUM. 


351 


with  perpendicular  medullary  layers  situated  one  behind 
the  other.  Behind  (or  above  when  we  stand  erect)  this  it\- 
tertexture,  a small  fasciculus  of  medullary  matter  exists^ 
Avhich  is  a continuation  of  the  posterior  fasciculus  of  the 
anterior  medullary  cord,  of  the  medulla  oblongata,  and 
may  be  traced  afterwards  to  the  superior  face  of  the  crus  ce- 
rebri. 

i 

SECT.  tv. — OF  THE  CEREBELLUM. 

The  Cerebellum,  being  placed  in  the  posterior  fossae  of 
the  cranium,  is  separated  by  the  tentorium  from  the  poste- 
rior lobes  of  the  cerebrum,  beneath  which  it  lies.  It  is 
continuous  with  the  Pons  Varolii  by  a trunk  of  medullary 
matter  on  each  side  proceeding  backwards  and  called  the 
crus  of  the  cerebellum,  which  is  a root  of  the  medullary 
matter  entering  into  the  composition  of  the  latter. 

It  is  of  a rounded  form,  and  well  fitted  to  the  cavity  in 
which  it  reposes.  It  is  convex  above  and  below;  measures 
about  four  inches  in  its  transverse  diameter,  two  and  a half 
in  thickness,  and  about  the  same  from  before  backwards. 
The  upper  surface  is  divided  into  two  equal  parts  or  halves, 
by  a middle  ridge,  while  the  lower  surface  is  divided  in  the 
same  way  by  a fossa.  These  halves  are  called  hemispheres; 
their  surface  is  marked  by  many  horizontal  fissures,  the 
edges  of  which  are  kept  closed  by  the  adhesion  of  the  pia 
mater. 

The  fissures  are  interposed  between  the  laminae  or  con- 
volutions of  the  cerebellum,  which  for  the  most  part  are 
concentric,  so  that  the  larger  are  behind,  Avhile  the  short- 
est are  in  front,  near  the  annular  protuberance.  The  pia 
mater  penetrates  to  the  bottom  of  these  fissures,  some  of 
Avhich,  when  exposed  fully  by  its  removal,  are  found  to  ex- 
tend to  the  depth  of  an  inch  or  more.  One  of  these  fissures, 
which  exists  on  the  superior  surface  of  the  cerebellum, 
half  an  inch  distant  from  the  posterior  and  external  margin 
of  the  latter;  has  a circular  course,  and  is  so  well  marked 
by  its  size  and  depth  that  it  is  called  the  Sulcus  Superior 


NERVOUS  SYSTEM. 


Cerebelll.  Another,  situated  under  similar  circumstances 
o,n  the  inferior  surface  of  the  cerebellum,  is  called  the  Sul- 
cus Inferior  Cerebelli.  On  the  latter  surface,  also,  there 
are  two  or  three  more  of  a middle  size,  situated  between 
the  sulcus  inferior  and  the  tuber  annulare.  These  larger 
sulci  have  given  occasion  to  anatomists  to  multiply  most  un- 
reasonably the  number  of  lobes  of  which  the  cerebellum 
consists.  Bichat’s  mode  of  description  is  preferable:  he  says, 
that  by  cutting  (vertically)  through  one  of  the  hemispheres 
of  the  cerebellum,  so  as  to  expose  the  thickest  part  of  its 
medullary  matter,  that  six  or  seven  principal  fissures  will  be 
seen,  which,  by  penetrating  to  a considerable  depth,  divide 
the  cineritious  portion  into  as  many  concentric  parts.  In 
the  interior  of  these  fissures  there  are  much  smaller  ones, 
which  pass  at  right  angles  to  them.  On  the  surface  or  pe- 
riphery of  the  cerebellum,  in  the  intervals  of  the  larger 
fissures,  there  are  many  small  ones,  which  though  general- 
ly horizontal,  terminate  in  each  other  by  acute  angles.  The 
superior  middle  ridge  of  the  cerebellum  from  its  shape  and 
position  is  called  by  Vicq.  D’Azyr,  Vermis  Superior;  the 
anterior  extremity  of  which,  from  its  elevation,  is  the  Mon- 
ticulus  Cerebelli. 

The  Valve  of  Vieussens  (called  also  velum  medullare, 
valvula  cerebri)  arises  from  the  cerebellum,,  just  under  the 
anterior  part  of  the  base  of  the  monticulus,  and  runs  ob- 
liquely upwards  to  terminate  in  the  testes.  Sometimes  it 
is  marked,  in  its  middle,  by  a longitudinal  line  or  slight 
fissure,  from  either  side  of  which  proceed  small  lateral  ones. 
It  Is  principally  medullary,  and  has  a small  quantity  of  cine- 
ritious matter  at  its  extremities.  It  is  thinner  in  the  mid- 
dle than  at  either  of  its  margins. 

The  middle  inferior  part  of  the  cerebellum,  which  pre- 
sents the  deep  sulcus  running  longitudinally  and  forming 
the  division  into  hemispheres,  has  a long  ridge  occupying 
the  sulcus.  This  ridge  is  the  Vermis  Inferior  of  Vicq. 
B’Azyr,  and  is  so  concealed  by  the  adjacent  portions  of  the 


THE  CEREBELLITil. 


353 


hemispheres,  that  a good  view  of  it  can  be  got  only  by  re- 
moving the  pia  mater  and  pushing  the  hemispheres  aside. 
The  transverse  fissures  which  penetrate  it,  and  its  general 
irregularity  of  surface,  will  then  be  sufficiently  distinct. 
The  pia  mater  passes  from  the  fore  part  of  this  body  to  the 
medulla  oblongata,  and  thus  assists  in  forming  the  floor  to 
the  fourth  ventricle;  which,  without  this  reflection,  would 
be  exposed.  The  central  part  of  the  cerebellum,  formed 
by  the  vermis  superior  and  by  the  vermis  inferior,  is  the 
Fundamental  Portion  of  Gall  and  Spurzheim. 

The  substance  of  the  cerebellum  is  formed  of  cineritious 
matter  externally, and  of  medullary  matter  internally.  When 
a vertical  section  of  it  is  made  through  the  middle  of  one  of  its 
hemispheres,  the  medullary  matter  puts  on  the  appearance  of 
the  thuya  or  arbor  vitae,  the  roots  and  ramifications  of  whose 
limbs,  even  to  their  smallest  extremities,  are  surrounded  by 
cineritious  matter.  In  this  view,  there  appears  to  be  more  ci- 
neritious than  white  matter;  butwhen  a horizontal  cut  is  made 
from  the  periphery  to  the  centre,  parallel  with  one  of  the 
deep  concentric  fissures,  the  proportion  of  medullary  matter 
seems  to  be  much  more  considerable;  and  the  arbor  vitae 
arrangement  is  proved  to  depend  upon  the  laminae  of  me- 
dullary matter  radiating  from  the  centre,  or,  in  other  words, 
from  the  massive  medullary  trunk  in  the  interior  of  the 
hemisphere  of  the  cerebellum.  Each  of  these  radiations 
commences  by  a root  of  considerable  size,  which  divides 
and  subdivides  into  branches.  Each  primitive  radiation, 
• as  well  as  its  branches,  is  covered  by  its  own  layer  of  cine- 
ritious matter  about  one  line  in  thickness,  and  is  kept  per- 
fectly distinct  from  the  contiguous  ones  by  the  fissures  which 
extend  internally  from  the  periphery  of  the  cerebellum. 

In  the  middle  of  the  trunk  of  the  arbor  vitas,  exists  the 
Corpus  Rhomboideum,  or  Dentatum.  It  is  an  oblong  rounded 
body,  and  jagged  and  cineritious  in  its  circumference,  but 
medullary  within.  Its  configuration  resembles  that  of  the 
corresponding  body  in  the  corpus  olivare,  with  the  addition 
of  its  being  larger,  and  having  its  outline  better  marked.  It 
is  the  ganglion  of  the  cerebellum  of  Gall  and  Spurzheim. 
VoL.  II.— 45 


XKKVOUS  SYSTEM. 


."i  j4 

The  Central  or  Fundamental  Portion  of  the  Cerebellum 
exhibits  also  very  clearly  the  arborescent  arrangement,  and 
is  furnisned  with  about  seven  primitive  radiations,  coming 
from  a inedullary  trunk.  The  proportion  of  medullary 
matter  to  cortical,  is  less  in  it  than  in  the  hemispheres  of 
the  cerebellum.  Each  of  the  primitive  radiations  may  be 
traced  to  some  particular  point  or  prominence  on  the  sur- 
face of  the  fundamental  portion,  thus  forming  its  basis;  but 
this  study  is  more  curious  than  useful,  though  several  ana- 
tomists have  pursued  it. 

The  medullary  mass  of  the  cerebellum  has,  on  each  side, 
three  fasciculi:  one  of  these  comes  from  the  corpus  resti- 
forme  of  the  medulla  oblongata;  a second  ascends  as  the 
valvula  cerebri  to  join  the  testes;  and  the  third,  called  the 
Crus  Cerebelli,  runs  to  join  the  annular  protuberance.  The 
two  first  fasciculi  belong  to  the  middle  or  fundamental  por- 
tion of  the  cerebellum;  they  are  consequently  situated  more 
internally,  and  are  partially  concealed  by  the  crus  cerebel- 
li, and  have  interposed  between  them  and  the  latter,  the 
Corpus  Rhomboideum,  or  Dentatum. 

SECT.  V. or  THE  CEREBRUM. 

The  Cerebrum  weighs  about  three  pounds,  and  is  seven 
times  as  heavy  as  the  cerebellum.  It  is  ovoidal,  and  mea- 
sures about  six  inches  in  its  antero-posterior  diameter,  five 
inches  in  its  greatest  breadth,  which  is  behind,  and  four  or 
five  ill  depth.  It  is  separated  above  by  a deep  fissure,  (Fis- 
sura  Longitudinalis,)  into  two  equal  parts  called  Hemis- 
pheres. At  the  bottom  of  this  fissure,  by  separating  the  con- 
tiguous surfaces  of  it,  is  to  be  seen  a broad  lamina  of  me- 
dullary matter  passing  from  side  to  side  and  called  the  Cor- 
pus Callosum,  which  connects  the  two  hemispheres  toge- 
ther. The  under  surface  of  each  hemisphere  is  subdivided 
into  three  lobes;  Anterior,  Middle,  and  Posterior. 

The  anterior  lobes  are  placed  upon  the  anterior  fossae  of 
the  base  of  the  cranium;  the  Middle,  upon  the  middle 
fossae  of  the  same;  and  the  Posterior  Lobes  rest  upon  the 


THE  CEREBRUM. 


355 


tentorium.  The  two  anterior  lobes  are  completely  sepa- 
rated by  the  Fissura  Longitudinalis,  which  extends  be- 
tween them  to  the  base  of  the  cranium;  the  same  is  the 
case  with  the  posterior  lobes;  the  middle  lobes  have  inter- 
posed between  them  the  annular  protuberance  and  the  crura 
cerebri.  When  the  pia  mater  is  removed,  the  anterior  lobe 
is  seen  to  be  marked  off  from  the  middle  lobe  by  a deep 
sulcus,  in  the  under  surface  of  the  cerebrum,  correspond- 
ing, in  its  position,  with  the  posterior  margin  of  the  Lesser  . 
Sphenoidal  Wing.  The  boundary  between  the  middle  and 
the  posterior  lobe  is,  by  no  means,  well  defined  on  the  basis 
of  the  brain,  but  it  is  agreed  to  consider  as  posterior  lobe, 
all  that  part  of  the  hemisphere  which  rests  upon  the  tento- 
rium. 

The  periphery  of  the  cerebrum  is  formed  into  convolu- 
tions [Gyri)  which  give  it  an  unequal  tortuous  surface,  re- 
sembling the  intestines  of  a small  child.  These  convolu- 
tions are  separated  by  fissures  [Sulci)  of  depths  varying  from 
an  inch  to  two  inches  or  more.  The  convolutions  proceed 
in  diversified  and  complicated  courses,  which  never  cor- 
respond in  different  individuals,  and  seldom  on  the  two  he- 
mispheres of  the  same  brain.  Though  their  summit  is  ge- 
nerally convex,  yet  some  of  them  have  it  depressed  slightly, 
which  is  considered  a proof  of  each  convolution  being  divi- 
sible into  two  halves  or  layers,  placed  side  by  side.  Some 
of  the  convolutions  are  short,  others  long;  they  present  nu- 
merous varieties  in  the  manner  of  joining  each  other.  Owing 
to  the  narrowness  of  the  fissures  between  them,  they  are 
closely  packed  together,  so  that  the  lateral  surfaces  of  each 
one  are  suited  to  such  as  are  contiguous;  occasionally  there 
is  a departure  from  this  rule. 

The  surface  of  the  convolution,  by  which  we  mean  not 
only  the  most  exterior  periphery  of  the  cerebrum,  but  also 
the  surfaces  formed  by  the  fissures  to  their  very  bottom,  is 
covered  by  cineritious  matter  of  about  one  line  in  thick- 
ness. 

Within  the  periphery  of  the  cerebrum,  the  mass  of  medul- 
lary matter  is  very  considerable,  and  is  of  an  ovoidal  shape. 


356 


NERVOUS  SYSTEM. 


This  ovoid  is  called  the  Centrum  Ovale  of  Vieussens,  and 
is  brought  fairly  into  view  by  making  a horizontal  cut 
through  the  hemispheres,  two  inches  below  their  summit. 

In  proceeding  with  the  anatomy  of  the  cerebrum  from 
its  base  upwards  the  following  is  the  order  or  succession  of 
parts  in  its  structure:  In  advance  of  the  pons  varolii,  and 
springing  from  it,  there  are  two  divergent  medullary  trunks, 
one  on  each  side,  which  run  forwards,  and  are  lost  in  the 
medullary  substance  of  the  cerebrum.  These  trunks  are  the 
crura  cerebri,  upon  the  upper  surface  of  which  are  two  pro- 
tuberances: the  posterior  is  the  thalamus  nervi  optici,  and 
the  anterior  is  the  corpus  striatum.  Each  crus  cerebri, 
having  penetrated  into  the  substance  of  its  respective  he- 
misphere, expands  by  a multiplication  of  the  filaments  com- 
posing it,  so  as  to  constitute  the  principal  bulk  of  the  he- 
misphere. These  filaments  may  indeed  be  traced  very  sa- 
tisfactorily in  almost  every  direction  towards  the  periphery 
of  the  cerebrum,  where  they  terminate  in  the  convolutions, 
their  extremities  being  covered  by  the  cineritious  matter 
there.  The  arrangement  is  best  seen  by  scraping  with  a 
knife  along  the  base  of  the  brain,  especially  when  the  latter 
has  been  hardened  in  spirits  of  wine,  and  it  is  constituted  by 
what  are  called  by  M.  M.  Gall  and  Spurzheim  the  diverging 
fibres  of  the  brain. 

The  point  is  not  indeed  entirely  settled  that  the  diverging 
filaments  end  in  the  convolutions,  or  do  not  rather  after- 
wards inflect  or  double  on  themselves,  and  pass  inwards 
again  to  the  middle  line  of  the  brain,  forming  by  their  con- 
vergence the  corpus  callosum.  At  all  events,  the  fact  is 
quite  demonstrable  that  as  the  under  and  lateral  portions  of 
the  hemisphere  consist  in  diverging  filaments,  arising  in 
and  from  the  crus  cerebri,  so  the  upper  portion  and  the  cor- 
pus callosum  consist  in  filaments  which  arise  in  the  adjoin- 
ing convolutions,  and  collect  towards  the  middle  of  the  cor- 
pus callosum,  where  they  adhere  to  the  congeneric  filaments 
of  the  other  side. 

The  arrangement  is  in  the  most  simple  conception  and 
illustration  of  it  what  would  be  exemplified  by  folding  a strip 


THE  CEREBRUM. 


357 


of  cloth  double  on  itself,  so  as  to  convert  it  into  a loop; 
the  under  part  of  the  loop  would  then  represent  the  di- 
verging fibres  of  the  cerebrum  and  the  upper  part  the  con- 
vero'ing  fibres,  or  corpus  callosum;  it  being  at  the  same  time 
borne  in  mind  that  the  continuation  of  the  two  orders  of 
fibres  into  one  another  in  the  brain  is  not  so  fully  ascer- 
tained as  it  would  be  represented  by  this  model. 

Between  the  two  orders  of  fibres  there  is  a horizontal 
cleft  or  interval.  This  interval  is  the  lateral  ventricle  of 
the  hemisphere,  which  may  be  got  into  under  the  posterior 
margin  of  the  corpus  callosum,  from  its  being  open  there; 
or  rather  only  closed  by  an  adhesion  of  the  membranes, 
which  is  easily  lacerated. 

The  preceding  is  intended  as  a mere  outline  upon  which 
to  form  the  base  of  the  descriptive  anatomy  of  the  cere- 
brum. The  following,  therefore,  may  be  considered  as  the 
detailed  account. 

The  Crura  Cerebri  are  rounded  below;  about  eight  lines 
long,  and  increase  in  their  transverse  diameter  as  they 
advance;  their  vertical  diameter  is  about  ten  lines.  They 
mutually  diverge,  beginning  from  their  roots,  and  are  se- 
parated by  a deep  fissure,  considered  as  a continuation  of 
that  on  the  front  of  the  medulla  oblongata.  This  fissure  is 
the  third  ventricle  of  the  brain.  Their  surface  is  marked 
by  superficial  furrows,  running  longitudinally;  and  about 
two  lines  before  the  tuber  annulare,  by  a transverse  fasci- 
culus of  medullary  matter,  very  slightly  elevated;  the  optic 
nerves  also  cross  them  obliquely  at  their  fore  part. 

In  regard  to  texture,  the  crus  cerebri  presents,  on  its  un- 
der surface,  a medullary  layer  of  two  lines  in  thickness;  to 
this  succeeds  a parcel  of  cineritious  matter,  which,  on  being 
removed,  is  followed  by  a mixture  of  both  cineritious  and 
white  matter,  more  abundant  than  either  of  the  preceding. 

The  Eminentis  Mammillares,  or  Corpora  Albicantia,  are 
two  small  bodies,  one  on  each  side,  about  the  size  of  a 
French  pea.  They  are  situated  near  the  anterior  extremi- 
ties of  the  crura  cerebri,  on  their  internal  faces,  and  almost 


NERVOUS  SYSTEM. 


OOt) 

in  contact  with  each  other.  Their  texture  is  medullary 
without,  and  cortical  within. 

The  Infundibulum  is  placed  immediately  before  the  emi- 
nentiae  mammillares.  It  is  a flattened  conoidal  body  half 
an  inch  long,  with  its  base  upwards,  and  its  apex  going 
downwards  and  forwards.  It  is  formed  of  cineritious  mat- 
ter. Most  generally  its  base  is  hollow,  and  opens  into  the 
third  ventricle,  but  its  point  is  closed.  J.  F.  Meckel,  how- 
ever, asserts  that  a communication  exists  entirely  through 
it,  from  the  pituitary  gland  to  the  third  ventricle,  and  that 
he  has  frequently  proved  it  by  passing  air  or  liquids  from 
this  gland,  though  the  experiment  does  not  succeed  when 
he  attempts  the  injection  from  the  third  ventricle. 

The  Pituitary  Gland  {Glandula  Pituitaria)  is  situated 
in  the  Sella  Turcica,  and  is  covered  so  completely  by  the 
dura  mater,  that  only  a small  aperture  is  left  for  the  point 
of  the  infundibulum  to  pass  through  and  to  adhere  to  it.  It 
is  an  ovoidal  body,  the  greatest  diameter  of  which  is  trans- 
verse, and  amounts  to  six  lines.  It  is  partially  divided,  so 
as  to  give  the  appearance  of  two  lobes,  of  which  the  ante- 
rior is  much  the  larger.  It  is  hard  and  cineritious,  with  a 
small  quantity  of  medullary  matter  within.  In  either  side 
of  it  there  is  a depression  from  which  leads  a small  canal 
towards  the  place  where  the  infundibulum  joins  it;  the  two 
canals  are  in  the  latter  place  united  into  one.  In  some  very 
rare  cases  gritty  matter  has  been  found  in  it,  as  there  is  in 
the  pineal  gland.  It  is  also  surrounded  by  pia  mater. 

The  Tuber  Cinereum  or  PonsTarini,  is  a portion  of  the 
under  surface  of  the  crus  cerebri,  at  the  floor  of  the  third 
ventricle.  It  is  continuous  in  front  with  the  anterior  mar- 
gin of  the  corpus  callosum.  In  front  of  the  infundibulum 
the  optic  nerves  unite,  after  having  crossed  obliquely  the 
crura  cerebri  from  without  inwards  and  forwards.  In  this 
passage,  where  they  reach  the  middle  of  the  crura,  and  at 
the  internal  border  of  the  same,  they  come  in  contact  with 
the  tuber  cinereum,  from  which  they  get  a few  filaments, 
but  of  this  more  hereafter. 


THE  CEREBRUM. 


359 


The  Thalami  Optici,  called,  by  Gall,  the  Posterior  Gan- 
glions of  the  brain  {Ganglia  Postica)  are  amongst  the  most 
conspicuous  parts  of  the  internal  structure  of  the  cerebrum, 
and  are  two  in  number,  one  for  either  side.  They  are  si- 
tuated on  the  superior  face  of  the  crura  cerebri,  are  about 
an  inch  and  a half  long  from  behind  forwards;  and  about 
eight  or  ten  lines  broad  and  deep* 

The  Thalami  are  convex  above  and  internally.  At  the 
junction  of  these  two  surfaces  is  observed  a medullary  line, 
described  under  the  name  of  peduncle  of  the  pineal  gland. 
Their  posterior  extremity  is  likewise  convex,  and  is  divided 
into  three  rounded  prominences;  one  is  above  the  other  two, 
and  is  the  Tuberculum  Posterius  Superiiis;  the  second  is 
below  and  within  {Corpus  Geniculatum  Internum)  and 
the  third  is  below  and  external  {Coipus  Geniculatum  Ex- 
ternum.) There  is  a fourth  tubercle  Tuberculum  Ante- 
rius)  which  is  situated  on  the  upper  convex  surface  of  the 
thalamus;  it  is  produced  by  the  fan-like  termination  of  a 
large  medullary  fasciculus  which  comes  from  the  eminentia 
mammillaris. 

The  thalami  are  somewhat  flattened  on  the  middle  of  their 
convex  internal  surface,  and  adhere  there  to  each  other  by 
a layer  of  cineritious  substance  called  Commissura  Mollis. 
When  the  brain  is  very  slightly  advanced  in  putrefaction, 
or  has  been  made  soft  by  dropsy,  this  junction  scarcely 
seems  to  exist  at  all. 

The  thalami  are  medullary  on  the  surface  presented  to 
the  ventricles  of  the  brain,  but  within  they  are  a mixture  of 
cineritious  with  medullary  matter.  The  fibres  of  the  me- 
dullary are  very  intimately  blended  with  the  crura  cerebri, 
and  radiate  from  within  towards  the  circumference  of  the 
brain;  some  of  them  are  placed  in  layers,  and  are  connected 
with  the  tubercula  quadrigemina. 

The  Corpora  Striata,  or  the  Ganglia  Cerebri  Antica,  also 
two  in  number,  one  for  each  side  or  hemisphere  of  the  brain, 
are  situated  before  the  thalami  optici,  at  the  bottom  of  the 
lateral  ventricles.  They  are  about  two  and  a half  inches 
long,  convex  on  their  upper  surface,  and  eight  lines  broad 


SCO 


NERVOUS  SYSTEM. 


broad  at  their  front  part,  but  taper  very  gradually  to  a point 
behind.  They  are  about  four  lines  apart  in  front,  and  are 
separated  there  by  the  septum  lucidum,  but  their  posterior 
extremities  diverge  from  each  other,  so  as  to  admit  the 
thalami  optici  between  them. 

The  surface  of  the  corpus  striatum  is  cineritious,  but 
within  it  consists  of  cineritious  and  of>  medullary  matter, 
placed  in  layers  which  alternate  with  each  other.  These 
layers  are  arranged  in  a crescentic  manner,  so  as  to  present 
the  convexity  upwards  and  the  concavity  downwards.  The 
medullary  substance  is  a continuation  of  that  of  the  crus 
cerebri  and  of  the  optic  thalamus.  It  enters  at  the  posterior 
inferior  part  of  the  corpus  striatum,  and  immediately  divides' 
into  three  layers,  placed  ofte  above  the  other,  and  of  which 
the  two  inferior  are  more  narrow  and  short  than  the  supe- 
rior. The  upper  layer,  in  its  progress  forwards,  is  inter- 
rupted by  a body  of  cineritious  substance,  which  occasions 
it  to  divide  into  a multitude  of  distinct  radiated  fibres.  The 
same  circumstance  attends,  the  other  layers,  but  in  a more 
limited  degree.  The  medullary  matter  of  the  corpus  stria- 
tum may  then  be  traced,  in  all  directions,  into  the  hemi- 
spheres of  the  brain.  The  cineritious  substance  of  the  cor- 
pus striatum  is  abundant,  and  is  divided  by  some  anatomists 
into  two  kinds,  one  of  a light  gray,  and  another  of  a darker 
colour.  The  first  forms  the  middle  and  inferior  part  of  the 
corpus  striatum;  the  second  is  in  greater  quantity,  and  is 
found  principally  above  and  between  the  two  upper  lay- 
ei’s.  Such  is  the  general  plan  of  the  structure  of  the  corpus 
striatum;  but,  it  should  also  be  understood,  that  a close  in- 
tertexture exists  between  its  medullary  and  cineritious 
matter. 

The  most  satisfactory  way  of  unravelling  the  structure  of 
the  corpus  striatum,  is  to  scrape  away  its  under  surface,  in 
tracing  its  medullary  matter  from  the  crus  of  the  brain,  and 
through  the  optic  thalamus.  It  will  then  be  seen,  that  the 
medullary  substance  of  the  crus  reaches  the  posterior  infe- 
rior part  of  the  corpus  striatum,  and  is  immediately  invested 
in  the  greater  part  of  its  circumference  with  cineritious  mat- 


THE  CEREBRUM. 


361 


ter,  it  then  begins  to  expand  after  the  manner  of  a fan  into 
filaments.  These  filaments  or  fasciculi  penetrate  the  cine- 
ritious  matter  in  various  directions,  besides  those  just  de- 
tailed. A particular  exposition  of  them  is  given  by  Gall  and 
Spurzheim,  in  their  anatomy  of  the  brain. 

The  Taenia  Striata  is  placed  in  the  angle  formed  between 
the  internal  margin  of  the  Corpus  Striatum,  and  the  external 
one  of  the  Thalamus  Opticus,  where  these  two  bodies  are  in 
contact  and  continuous  with  one  another.  It  is  a small  me- 
dullary band,  not  a line  in  breadth,  commencing  nea-r  the 
anterior  crura  of  the  fornix,  with  which  it  is  connected  fre- 
quently by  filaments,  and  observing  the  curved  course  of 
the  fissure  in  which  it  is  placed,  it  goes  to  the  posterior  end 
of  the  corpus  striatum,  and  even  beyond  it  in  most  cases, 
by  uniting  itself  to  the  top  of  the  Cornu  Ammonis. 

The  Corpus  Callosum.  When  the  fissure  between  the 
hemispheres  of  the  cerebrum  is  widely  separated,  or  when 
the  superior  part  of  the  hemisphere  is  cut  away  on  a level 
with  the  bottom  of  the  fissure,  the  Corpus  Callosum,  a me- 
dullary layer,  is  brought  fully  into  view.  This  bod)^  unites 
the  medullary  mass  of  the  two  hemispheres,  and  is  a large 
commissure.  It  occupies  about  two-fifths  of  the  long  dia- 
meter of  the  brain,  being  nearer  to  its  anterior  than  to  its 
posterior  end,  and  is  about  eight  lines  broad,  increasing 
however  somewhat  in  breadth  posteriorly.  The  lateral  half 
of  it,  on  either  side,  is  concealed  by  the  hemisphere  over- 
lapping it,  but  is  prevented  from  adhering  by  a horizontal 
fissure  which  extends  from  one  end  to  the  other.  It  has  an 
arched  form,  being  convex  above  and  concave  below.  Its 
thickness  is  uniformly  about  three  lines,  with  the  exception 
of  its  anterior  and  its  posterior  margins,  which  are  more. 

The  middle  line  of  its  upper  surface  is  marked  out  from 
one  end  to  the  other  by  a very  slight  depression,  the  Raphe; 
on  each  side  of  which  there  is  a very  small  linear  elevation 
of  the  same  extent,  but  slightly  curved  inwards  towards  its 
fellow.  From  these  longitudinal  lines  there  proceed  out- 
wardly transverse  ones,  having  a fibrous  appearance.  At 
VoL.  II. — 46 


362 


NEKVOUS  SYSTEM. 


the  anterior  and  posterior  ends  of  the  corpus  callosum,  the 
latter  are  somewhat  curved  and  radiate  towards  the  peri- 
phery of  the  brain.  Other  longitudinal  lines  also  exist  on 
this  surface  of  the  corpus  callosum,  but  they  are  not  seen 
with  equal  facility.  The  anterior  extremity  of  the  corpus 
callosum  is  rounded  off,  and  bent  downwards  towards  the 
basis  of  the  brain,  in  such  manner  as  to  present  backwards 
its  concavity;  which  thus  embraces  the  fore  part  of  the  cor- 
pora striata,  and  closes  the  lateral  ventricles  at  this  point. 
The  posterior  end  of  the  corpus  callosum  is  rounded,  also, 
and  continuous  with  the  fornix  and  with  the  cornu  ammonis. 

By  examining  the  Corpus  Callosum  from  below,  or  by 
looking  at  its  relative  situation  and  shape  on  a hemisphere 
which  is  accurately  separated  from  its  fellow  in  the  middle 
line,  it  will  be  seen  that  its  lower  surface  is  very  concave, 
being  highly  arched  from  before  backwards;  that  it  forms 
■the  roof  of  the  lateral  ventricles,  and  that  this  surface  of  it 
is  about  two  inches  in  its  transverse  diameter,  and  therefore 
more  than  twice  as  broad  as  the  upper  surface. 

The  Fornix  ( Trigone  Cerebral.,  of  the  French)  is  placed 
immediately  below  the  corpus  callosum.  It  is  a triangular 
body  of  medullary  matter,  the  base  of  which  is  behind  and 
the  apex  in  front.  It  is  about  an  inch  and  a half  long  in 
its  bod}r,  and  one  inch  wide  at  its  base.  It  is  the  latter 
part  which,  lying  immediately  beneath  the  posterior  end  of 
the  corpus  callosum,  is  continuous  with  it,  and  causes  the 
fornix  to  be  considered  as  a part  of  the  same  structure  with 
the  corpus  callosum.  These  two  bodies,  which  may  be 
compared  to  a sheet  of  medullary  matter  doubled  on  itself, 
have  their  surfaces  in  contact  for  a short  distance  behind, 
the  fornix  afterwards,  by  advancing  and  keeping  itself  in 
close  contact  with  the  thalami  nervorum  opticorum,  which 
are  just  below  it,  diverges  more  and  more  from  the  under 
surface  of  the  corpus  callosum.  It  conceals  all  the  upper 
surface  of  the  thalami  except  their  external  margin,  and, 
having  reached  their  anterior  extremity,  its  apex  descends 
towards  the  basis  of  the  brain. 


THE  CEREBRUM. 


363 


The  body  of  the  fornix  is  about  a line  thick,  but,  at  its 
anterior  extremity,  it  becomes  somewhat  cylindrical,  and 
is  divided  into  two  columns,  called  Crura  Fornicis  Anterio- 
ra.  Each  of  these  crura,  in  descending  adheres  to  the  an- 
terior extremity  of  the  thalamus  of  that  side,  and,  getting 
finally  below  it  into  the  floor  of  the  third  ventricle,  it,  after 
a course  slightly  curved,  joins  the  cortical  substance  of  the 
Eminentiae  Mammillares.  Santorini,  aware  of  this  junc- 
tion, considered  the  eminentias  as  a part  of  the  fornix,  and 
therefore  called  them  Bulbi  Fornicis. 

The  fornix  has  other  attachments  of  a more  complex  de- 
scription, which  the  anatomist  should  attend  to,  as  they 
serve  to  indicate  the  modes  of  intercourse  between  the  se- 
veral parts  of  the  cerebrum.  Its  fibres  having  reached, 
and  probably  formed,  the  eminentise  mammillares;  one  fas- 
ciculus of  them  ascends  from  there  along  the  internal  face 
of  the  optic  thalamus,  invested  by  the  ciiieritious  matter  of 
the  latter,  and  spreads  itself  above  like  a fan,  and  forms  the 
tuberculum  anterius:  a second  fasciculus  from  the  same 
point,  having  divided  into  two  after  going  a short  distance, 
sends  one  division  backwards  along  the  upper  internal  face 
of  the  optic  thalamus,  to  join  the  peduncle  of  the  pineal 
gland,  and  the  other  division,  which  is  more  anterior,  runs 
to  join  the  tsenia  striata;  a third  fasciculus  from  the  eminen- 
tia  mammillaris,  being  covered  by  the  optic  nerve,  goes 
outwards  and  backwards  to  terminate  in  the  thalamus  nervi 
optici. 

The  posterior  margin,  or  the  base  of  the  fornix,  besides 
running  into  the  corpus  callosum,  has  the  angle  on  each 
side  elongated  so  as  to  rest  upon  and  to  join  the  upper  end 
of  the  cornu  ammonis.  The  angle,  being  continued,  then 
follows  the  winding  course  of  the  latter,  adhering  to  its 
posterior  margin,  but  hanging  loosely  over  the  anterior. 
This  loose  edge  or  continuation  of  the  external  margin  of 
the  fornix  is  the  Taenia  Hippocampi,  or  Corpus  Fimbri- 
atum.  The  elongations  of  the  posterior  angles  are  called 
Crura  Posteriora  Fornicis.  In  the  brains  of  individuals 
who  have  suffered  from  general  dropsy,  one  frequently  finds 
the  fornix  narrower  than  usual,  and  in  its  middle  a fissure 
which  separates  almost  completely  its  two  halves. 


3t34 


NERVOUS  SYSTEM. 


As  the  fornix  is  suited  to  the  upper  surface  of  the  optic 
thalamus,  it  is  of  course  concave  below  and  convex  above, 
or  resembles,  a triangular  arch  resting  upon  its  three  points 
or  angles.  Owing  to  som.e  misunderstanding  of  the  origi- 
nal Greek  word  which,  according  to  the  interpre- 

tation of  Sabatier,  means  a vault,  and  thereby  expresses 
the  whole  body,  anatomists  with  the  exception  of  him, 
have  generally  supposed  the  striated  under  surface  of  the 
fornix  to  be  meant  by  it,  and  have  called  this  surface  Lyra, 
in  which  mistake  one  has  followed  another. 

The  Septum  Lucidum  is  a partition  placed  vertically  in 
the  middle  line  of  the  brain,  and  extends  from  the  corpus 
callosum  above  to  the  fornix  below.  It  is  of  a triangular 
shape,  but  irregularly  so,  being  much  broader  before  than 
it  is  behind,  and  having  its  edges  so  incurvated  as  to  fit  the 
bodies  against  which  it  is  applied. 

The  septum  lucidum  is  formed  by  two  laminae  placed 
side  to  side,  but  not  adhering  to  each  other,  and  leaving 
therefore  an  interval  between  them,  called  the  Ventriculus 
Septi,  or  the  fifth  ventricle.  Each  of  these  laminae  con- 
sists of  two  layers;  the  internal  is  medullary  substance,  con- 
tinuous with  that  of  the  corpus  callosum  and  of  the  fornix; 
and  the  external  is  a layer  of  cineritious  substance.  The 
cavity  is  about  an  inch  and  a half  long  by  a line  wide,  and 
is  narrower  in  the  middle  than  at  either  extremity.  It  is 
lined  by  a delicate  serous  membrane,  which  becomes  mani- 
fest when  the  halitus  that  naturally  covers  its  surface  is  ac- 
cumulated into  a body  of  water.  It  is  generally  supposed 
to  be  insulated  or  completely  shut  up,  yet  occasionally  it 
has  been  found  elongated  in  front,  towards  the  space  be- 
tween the  anterior  commissure  and  the  anterior  crura  for- 
nicis,  and  to  communicate  there  with  the  third  ventricle.* 

The  Pineal  Gland  [Glandula  Pinealis,  Conarium)  is 
placed  beneath  the  posterior  margin  of  the  fornix,  upon  the 
superior  tubercula  quadrigemina  or  the  nates.  It  is  an  ob- 
long spheroidal  body,  the  long  diameter  of  which  is  trans- 


J.  F.  Meckel. 


THE  CEREBRUM. 


365 


verse,  and  amounts  to  three  or  four  lines,  while  the  short 
diameter  is  about  three  lines.  The  substance  of  the  pineal 
gland  is  cineritious,  and  of  a reddish  colour.  At  its  in- 
ferior part  there  is  a small  cavity,  sometimes  lined  with 
medullary  matter,  and  the  orifice  of  which  looks  towards 
the  third  ventricle. 

This  body  is  connected  to  the  adjacent  parts  by  several 
cords.  From  its  bottom  there  proceeds,  on  each  side,  the 
long  medullary  filament  called  its  peduncle,  which  runs 
along  the  upper  internal  face  of  the  thalamus  opticus,  and, 
as  observed,  joins  or  is  continuous  with  one  of  the  filaments 
from  the  Eminentise  Mammillares.  From  its  base  there 
proceeds  a transverse  lamina  of  medullary  matter,  called 
the  Posterior  Commissure  of  the  brain,  which  first  advances 
forwards,  and  then  recedes,  so  as  to  be  in  some  measure 
doubled  on  itself.  This  lamina,  at  either  end,  is  united 
to  the  upper  posterior  part  of  the  corresponding  optic  tha- 
lamus, and  by  its  lower  margin  runs  into  the  superior  edge 
of  the  tubercula  quadrigemina. 

Within  the  pineal  gland,  and  sometimes  on  its  surface, 
there  is  an  accumulation  of  calcareous  matter,  the  Acervu- 
lus  Cerebri,  that  appears  about  the  sixth  year  of  life,  and 
continues  for  ever  afterwards.  It  is  variable  both  in  quan- 
tity and  in  its  mode  of  concretion,  for  sometimes  there  are 
only  a few  atoms  of  grit,  scarcely  distinguishable  by  the 
feel;  while  on  other  occasions  it  is  collected  into  a body  of 
irregular  shape,  and  more  than  a line  in  diameter.  The 
pieces  of  which  the  acervulus  consists,  are  sometimes  united 
by  cellular  substance,  and  enclosed  in  a sac.  Their  chemi- 
cal analysis  presents  phosphate  of  lime  in  large  proportion, 
carbonate  of  lime,  and  animal  matter. 

A reflection  of  pia  mater,  the  Velum  Interpositum,  sepa- 
rates the  pineal  gland  from  the  fornix,  and  the  fornix  from 
the  thalami  nervorum  opticorum. 

The  Tubercula  Quadrigemina  (or  the  Nates  et  Testes) 
are  situated  on  the  superior  face  of  the  crura  cerebri,  and 
just  behind  the  thalami  nervorum  opticorum.  A very 


NERVOUS  SYSTEM. 


obG 

complete  view  of  them  is  obtained  by  separating  the  poste- 
rior lobes  of  the  cerebrum,  and  by  paring  off  the  vermis  su- 
perior eerebelli.  Though  the  name  implies  four  distinct 
prominences,  yet  they  are  formed  from  a common  mass  of 
nine  or  ten  lines  square,  on  the  posterior  surface  of  which 
these  prominences  arise.  They  are  in  pairs,  and  are  sepa- 
ted  from  one  another  by  a crucial  depression.  The  largest 
or  upper  pair  is  the  Nates,  the  lower  pair  the  Testes.  The 
external  surface  of  these  bodies  is  medullary,  and  within 
they  are  cineritious.  From  the  Nates  there  proceeds  a 
considerable  medullary  fasciculus,  which  runs  forwards  to 
join  the  Corpus  Geniculatum  Internum  on  the  internal  pos- 
terior face  of  the  thalamus  nervi  optici;  there  proceeds  also 
from  them  a second  fasciculus,  which  either  joins  the  optic 
nerve  itself,  or  the  contiguous  part  of  its  thalamus.  The 
Testes  receive,  at  their  lower  end,  the  valve  of  the  brain; 
and  there  also  proceeds  from  them  a large  fasciculus  of  me- 
dullary matter,  which  joins  the  corpus  geniculatum  exter- 
num of  the  optic  thalamus. 

Of  the  Ventricles  of  the  Brain. 

These  cavities  are  four  in  number,  two  called  lateral  arc 
placed  one  in  either  hemisphere  of  the  cerebrum,  a third  is 
between  the  two  thalami,  and  the  fourth  under  the  cere- 
bellum. They  have  all  been  alluded  to,  but  only  superfi- 
cially. 

The  Two  Lateral  Ventricles  (^Ventriculi  Laterales)  are 
horizontal  cavities  or  fissures  of  an  extremely  irregular 
shape,  in  the  very  centre  of  the  hemispheres,  being  the  in- 
terval between  the  diverging  and  converging  filaments  of  the 
cerebrum.  They  are  separated  from  each  other  only  by  the 
septum  lucidum;  are  covered  over  by  the  corpus  callosum, 
and  have  the  fornix,  thalami  optici,  and  corpora  striata  for 
a floor.  Each  one  consists  in  a body  or  principal  cavity, 
and  three  processes  called  cornua.  The  body  has  been  suf- 
ficiently described  in  speaking  of  the  parts  which  constitute 
its  parietes;  but  the  processes  are  yet  to  be  considered. 


THE  CEREBRUM. 


367 


The  Cornua,  from  their  position,  are  named  Anterior, 
Posterior,  and  Lateral  or  Inferior.  The  Anterior  is  a very 
small  space  between  the  anterior  extremity  of  the  corpus 
striatum  and  the  opposite  surface  of  the  hemisphere,  and  has 
nothing  in  it  particularly  deserving  of  notice.  The  Poste- 
rior Cornu  extends  from  the  base  of  the  fornix  to  the  dis- 
tance of  an  inch  or  more  in  the  substance  of  the  posterior 
lobe  of  the  cerebrum.  Its  cavity  is  conoidal,  somewhat 
curved,  with  its  convexity  outwards,  and  of  six  or  seven 
lines  in  diameter  in  its  base.  Its  internal  side  is  furnished 
with  an  oblong  eminence  called  Hippocampus  Minor,  or 
Ergot,  from  its  resemblance  to  a cock’s  spur,  but  its  size 
and  form  are  somewhat  variable.  When  this  eminence  is 
cut  through  transversely,  it  is  easy  to  see  that  it  is  formed 
by  a convolution  of  the  posterior  lobe  projecting  into  the 
posterior  cornu.  The  convolution  is  covered  by  medullary 
matter  on  the  side  of  the  ventricle,  and  of  course  by  cine- 
ritious  on  the  side  of  the  periphery  of  the  brain,  and  is  the 
bottom  of  an  anfractuosity. 

The  Inferior,  Middle,  or  Lateral  Cornu,  of  the  Lateral 
ventricle  is  situated  in  the  middle  lobe  of  the  cerebrum.  It 
commences  at  the  posterior  angle  of  the  fornix,  and  winds 
downwards  and  forwards  in  a semicircle  towards  the  fissure 
of  Sylvius,  presenting  its  convexity  outwards,  and  its  con- 
cavity within.  Its  floor  is  furnished  in  its  whole  length 
with  an  elevated  ridge,  the  surface  of  which  is  semicylin- 
drical.  This  ridge  is  the  Cornu  Ammonis,  or  Hippocampus 
Major,  and  increases  somewhat,  both  in  breadth  and  eleva- 
tion, as  it  winds  down  the  process  of  the  ventricle.  Its 
lower  or  anterior  extremity  is  terminated  by  two  or  three 
small  tubercles,  and  is  the  Pes  Hippocampi.  Occasionally 
the  hippocampus  major  is  marked  oflf  by  a middle  longitu- 
dinal fissure  into  two  elevations,  of  which  the  external  is 
the  smaller.  On  its  concave  side  there  is  a thin  edge  of 
medullary  matter,  continuous  with  the  external  margin  of 
the  fornix.  The  extremity  of  a knife  handle  may  be  insinu- 
ated for  a short  distance  between  this  edge  and  the  hippo- 


36S 


NERVOUS  SYSTEM. 


campus;  it  ceases  about  half  way  down  the  latter,  and  in  the 
natural  state  of  the  parts  is  concealed  by  the  plexus  cho- 
roides.  This  edge  is,  as  mentioned  in  the  account  of  the 
fornix,  the  Taenia  Hippocampi  or  Corpus  Fimbriatum.  Be- 
neath the  latter,  and  partially  covered  by  it,  there  is  another 
body,  which  presents  itself  in  the  form  of  a small  chord  of 
cineritious  matter,  it  is  not  quite  so  long  as  the  Taenia,  and 
is  called  Fascia  Dentata,  from  being  divided  into  several  sec- 
tions by  transverse  fissures,  which  give  it  an  undulating  ap- 
pearance. 

A transverse  incision  of  the  Hippocampus  Major  shows 
that  it  is  a body  of  cineritious  matter,  covered  on  its  sur- 
face by  a thin  layer  of  medullary  substance. 

The  Third  Ventricle  ( Ventriculus  Tertius. ) When  the 
fornix  is  separated  from  its  anterior  crura  and  turned  over 
backwards,  the  process  of  pia  mater,  called  Velum  Inter- 
positum,  is  found  between  it  and  the  optic  thalami.  This 
process  is  of  a triangular  shape,  resembling  the  fornix,  and 
is  about  the  same  size;  it  is  insinuated  into  this  place  from 
the  surface  of  the  brain,  under  the  posterior  margin  of  the 
corpus  callosum.  Its  lateral  margins,  which  project  beyond 
the  corresponding  ones  of  the  fornix,  are  formed  by  a con- 
geries of  convoluted  vessels,  constituting  the  plexus  cho- 
roides.  The  plexus,  indeed,  may  be  traced  from  the  pes 
hippocampi  along  the  corpus  fimbriatum  to  its  position  on 
the  margin  of  the  velum  interpositum;  and  insinuates  itself 
from  the  bottom  of  the  cerebrum  between  the  pons  varolii 
and  the  convolution  forming  the  hippocampus  major;  but 
when  it  reaches  the  anterior  end  of  the  fornix  its  convoluted 
character  ceases,  and  it  terminates,  on  each  side,  in  a single 
vein,  (vena  galeni,)  which  runs  from  before  backwards,  in  a 
straight  line,  near  the  middle  of  the  velum  interpositum. 
The  vein  finally  unites  with  its  fellow  to  form  a single  trunk, 
which  runs  into  the  fourth  sinus  of  the  dura  mater. 

The  Tela  Choroidea  or  Velum  Interpositum  adheres  very 
strongly  to  the  fornix,  by  means  of  small  vessels;  it  may  be 
raised  with  less  difficulty  from  the  thalami,  though  it  serves 


THE  CEREBRUM. 


otj9 

to  keep  the  third  ventricle  closed  above,  with  the  excep- 
tion of  the  part  just  behind  the  crura  of  the  fornix,  where 
the  third  and  the  lateral  ventricle  communicate  by  the  for- 
amen of  Monro.  The  pineal  gland  is  entangled  in  its  pos- 
terior part,  being  placed  below  it,  and  is  generally  torn  from 
its  peduncles  when  the  tela  is  raised  up.  It  is  at  this  point 
that  the  tunica  arachnoidea  may  be  traced  into  the  cavity 
of  the  lateral  ventricles. 

The  Plexus  Choroides,  which  was  stated  to  bound  the’ 
tela  choroidea  on  each  side,  and  to  descend  along  the  hippo- 
campus major  to  the  fissure  of-  Sylvius,  or  rather  to  ascend 
from  this  point,  and  to  terminate  in  the  vein  on  the  side  of 
the  middle  line  of  the  tela,  is  narrow  at  its  termination,  but 
increases  continually  ip  breadth  as  it  is  traced  towards  its- 
commencement.  The  middle  part,  however,  where  it  makes 
its  turn,  is  an  exception  to  this  rule,  for  there  it  is  larger 
in  every  way  than  elsewhere;  its  vessels  being  more  capa- 
cious and  more  tortuous.  Precisely  at  this  point,  a vesicle 
is  very  frequently  found,  considered  by  some  as  a hydatid 
of  the  brain;  in  some  cases  it  is  filled  with  calcareous  mat- 
ter instead  of  with  water.  The  Glandulfe  Pacchioni,  as 
stated,  also  prevail  at  this  margin. 

On  the  under  surface  of  the  tela  choroidea,  adhering  to  it, 
there  is  on  each  side  a small  venous  plexus  which  goes  from 
before  backwards,  and  terminates  in  the  vena  galeni,  near 
its  junction  with  its  fellow.  It  receives  the  blood  of  the 
third  and  of  the  fourth  ventricle.* 

There  is  also  the  same  sort  of  plexus  in  the  fourth  ventricle. 

Upon  the  removal  of  the  Velum  Interpositum,  or  its  ele- 
vation, the  pineal  gland  will  be  found  entangled  under  its 
posterior  margin,  and  the  whole  upper  surface  of  the  thalami 
optici  is  exposed;  the  third  ventricle  is  also  brought  into 
view,  of  which  much  has  already  been  said  in  speaking  of 
the  parts  which  constitute  it. 

The  third  ventricle  is  placed  immediately  between  the 
thalami  optici.  It  is  a narrow  oblong  cavity,  bounded  below 
by  the  pons  tarini,  crura  cei'ebri  and  the  eminentiae  mam- 

* Jileckel,  Manuel  D’Auatomie. 

VoL.  II.— 47 


NEKVOUS  SYSTEM. 


,170 

millares,  and  above  by  the  velum  interpositum  and  the  for- 
nix. The  anterior  crura  of  the  fornix  are  at  its  fore  part, 
and  just  before  them  is  the  anterior  commissure  (Commis- 
sura  tBnterior.)  This  body  is  a transverse  fasciculus  of 
medullary  matter,  which  passes  from  one  hemisphere  to 
the  other  through  the  anterior  margins  of  the  thalami  optici. 
Its  middle  part  is  rounded  and  free,  but  its  extremities  pe- 
netrate into  the  substance  of  the  anterior  inferior  portion  of 
the  corpus  striatum,  and  spreading  out  gradually,  describe 
a curve  with  its  convexity  forwards,  which  terminates  on 
each  side  in  the  taenia  hippocampi  of  the  inferior  cornu  of 
the  lateral  ventricle.  This  fasciculus,  in  penetrating  the 
corpus  striatum  does  not  mix  with  its  substance,  but  in  the 
early  part  of  its  course  goes  in  a canal  formed  in  the  latter. 
In  order  to  see  this  arrangement  a part  of  the  corpus  stria- 
tum must  be. removed.  The  anterior  commissure  resembles 
a nerve  in  its  structure,  as  it  is  surrounded  by  a very  deli- 
cate sheath,  and  is  divided  into  fasciculi  of  fibres. 

Just  behind  and  below  the  anterior  commissure,  the  base: 
of  the  infundibulum  opens  into  the  third  ventricle;  this  place 
is  the  Iter  ad  Infundibulum.  At  the  posterior  extremity  of 
the  third  ventricle,  just  below  the  posterior  commissure 
which  has  been  described  as  a process  of  the  pineal  gland, 
the  communication  exists  with  tjle  fourth  ventricle.  This 
passage  is  the  Aqueduct  of  Sylvius,  and  leads  obliquely 
downwards  and  backwards  under  the  valve  of  the  brain. 

The  third  ventricle  communicates  freely  with  the  lateral 
ventricle  through  the  aperture  called  the  Foramen  of  Mon- 
ro, which  is  situated  precisely  at  the  place  where  the  plexus 
choroides  terminates;  that  is  to  say,  under  the  anterior  crus 
of  the  fornix.  Doubts  have,  from  time  to  time,  been  sug- 
gested in  regard  to  the  natural  existence  of  this  commu- 
nication; it  only  requires  a moderate  degree  of  accurate  ob- 
servation to  dispel  them;  they  have  arisen,  probably,  from 
the  aperture  being  shut  up  by  the  occasional  adhesion  of  the 
the  plexus  choroides  to  the  contiguous  surface  of  the  brain. 

The  Fourth  Ventricle  ( Veniriculus  Quartus,  Cerebelli) 
has  been,  in  a great  degree,  described  in  the  account  of  the 


MERVES  OP  THE  ENCEPHALON. 


371 


neighbouring  parts;  it  will,  therefore,  be  very  readily  un- 
derstood on  the  present  occasion.  It  is  an  irregular  tri- 
angular cavity,  the  base  of  which  is  downwards.  It  is 
bounded  in  front  by  the  tuber  annulare  and  the  medulla  ob- 
longata, behind  by  the  fundamental  portion  of  the  cerebel- 
lum, and  above  by' the  valve  of  the  brain  and  the  tubercula 
quadrigeniina;  it  is  under  the  latter  that  the  communication 
between  it  and  ttie  third  ventricle  is  found.  Its  lateral  pa- 
rietes  are  formed  by  the  medullary  prolongations  from  the 
cerebellum  to  the  tubercula  quadfigemina.  This  cavity,  as 
stated,  is  open  below,  when  that  portion  of  pia  mater  is  re- 
moved, which  passes  from  the  cerebellum  to  the  medulla 
oblongata. 

From  what  has  now  been  said  of  the  connexion  of  the 
pia  mater  with  the  ventricles,  it  will  be  readily  understood 
that  as  their  surfaces  are  covered  by  pia  mater,  and  the  re- 
moval of  it  exposes  their  cavities,  they  are,  in  fact,  conti- 
nuations of  the  external  surface  of  the  brain. 

SECT.  VI. — OP  THE  NERVES  OP  THE  ENCEPHALON. 

The  more  improved  observations  of  modern  anatomists 
having  pointed  out  the  fallacy  of  considering  the  brain  as  the 
source  of  the  spinal  marrow,  instead  of  the  reverse,  it  will 
follow  that  the  proper  order  of  describing  the  nerves  of  the 
encephalon,  will  be  successively  from  the  spinal  marrow. 

The  Hypoglossal  Nerve  {Nervus  Hypoglossus,  or  Ninth 
Pair)  arises  from  the  medulla  oblongata,  by  several  fascicu- 
li placed  one  above  the  other.  The  roots  of  these  fasciculi 
spring  from  the  fissure  which  separates  the  corpus  pyrami- 
dale  from  the  corpus  olivare.  The  fasciculi  are  from  four 
to  eight  in  number,  being  subject  to  vary  in  different  indi- 
viduals. They  unite  into  two  or  three  trunks,  which  co- 
alesce into  one  after  penetrating  the  dura  mater  by  distinct 
openings;  and  then  proceed  through  the  anterior  condyloid 
foramen  of  the  occipital  bone. 

The  general  distribution  of  this  .nerve  is  to  the  muscles 
of  the  tongue. 


372 


3STEKV0US  SYSTEM. 


The  Accessory  Nerve  (Nermis  Accessorius,  Eighth  Pair) 
arises  from  the  posterior  fasciculus  of  the  Medulla  Oblon- 
gata, just  behind  the  nervus  hypoglossus,  and  also  from  the 
posterior  fasciculus  of  the  Medulla  Spinalis,  sometimes  as 
low  down  as  the  seventh  cervical  nerve.  There  are  six  or 
seven  roots  from  the  medulla  spinalis,  and  about  three  or 
four  from  the  medulla  oblongata;  the  former  are  single,  and 
run  successively  into  the  same  trunk;  but  the  latter  are  each 
composed  of  two  branches,  consisting  respectively  of  two 
filaments.  These  roots  are  successively  larger  and  longer 
as  they  ascend  to  join  the  common  trunk.  The  latter  goes 
up  between  the  posterior  fasciculi  of  spinal  nerves  and  the 
ligamentum  denticulatum,  and  gets  into  the  cavity  of  the 
cranium,  behind  the  vertebral  artery  through  the  foramen 
magnum  occipitis. 

This  nerve  varies  in  respect  to  the  number  of  its  roots, 
and  the  mode  of  their  origin.  In  all  cases  the  trunk  thus 
formed  passes  from  the  cranium  through  the  foramen  lace- 
rum  posterius,  traversing  there  the  dura  mater  in  a sheath 
common  to  it  and  to  the  pneumogastric  nerve,  but  some- 
times it  has  its  own  particular  opening  behind  that  of  the 
latter. 

Its  general  distribution  is  to  the  muscles  and  to  the  inte- 
guments of  the  neck. 

The  Pneumogastric  Nerve  {Nervus  Pneuniogastricus 
or  Vagus,  Eighth  Pair)  arises  from  the  corpus  restiforme 
of  the  Medulla  Oblongata,  just  behind  or  on  the  borders  of 
the  fissure  separating  it  from  the  Corpus  Olivare,  somewhat 
above  and  posterior  to  the  highest  root  of  the  accessory 
nerve.  It  commences  by  a number  of  parallel  filaments, 
varying  in  number  from  ten  to  fifteen,  which  are  placed  very 
near  each  other,  so  as  to  form  two  or  three  flattened  fasciculi 
of  half  an  inch  or  more  in  length.  The  fasciculi  below  ad- 
here to  the  spinal  accessory,  and  those  above  to  the  glosso- 
pharyngeal nerve.  The  fasciculi  finally  collect  into  a sin- 
gle flattened  cord  of  one  and  a half  lines  in  breadth. 

This  cord  goes  outwards  and  backwards  to  the  foramen 


3VERVES  OF  THE  ENCEPHALON. 


373 


iacerum  posterius,  and  gets  through  it  in  front  of  the  inter- 
nal jugular  vein,  being  separated  from  the  latter  by  the 
small  spine  which  arises  from  pars  petrosa  of  the  temporal 
bone.  It  passes  through  its  own  canal  in  the  dura  mater, 
being  thus  kept  distinct  from  the  glosso-pharyngeal,  and 
from  the  accessory  nerve,  and  in  this  canal  the  fasciculi 
which  form  it  are  collected  into  a single  cylindrical  trunk. 
After  getting  through  the  canal  it  then  adheres  by  a close 
strong  cellular  substance,  to  the  glosso-pharyngeal  and  to  the 
accessory. 

The  general  plan  of  distribution  of  the  Pneumogastric 
Nerve  is,  as  its  name  implies,  to  the  organs  of  respiration 
and  to  the  stomach. 

The  Glosso-Pharyngeal  Nerve  [Nervus  Glosso-Pharyn- 
geus,  Eighth  Pair)  arises  from  the  posterior  cord  of  the  me- 
dulla oblongata,  just  above,  and  somewhat  anterior  to  the 
superior  filaments  of  the  last  nerve,  with  which  it  is  very 
closely  connected.  Its  filaments,  which  are  five  or  six  in 
number,  spring,  therefore,  from  the  anterior  margin  of  the 
corpus  restiforme,  or  from  the  fissure  separating  it  from  the 
corpus  olivare,  under  the  posterior  margin  of  the  tuber  an- 
nulare. 

Its  filaments  soon  collect  into  a round  cord,  and  anasto- 
mose even  in  the  cavity  of  the  cranium  by  a considerable 
branch  with  the  pneumogastric.  It  runs  outwards  and  back- 
wards to  the  foramen  Iacerum  posterius,  and  goes  through 
the  same  division  of  it  that  the  pneumogastric  does,  but  in 
its  own  canal  of  the  dura  mater.  About  half  an  inch  from 
this  canal  it  enlarges  within  the  cranium,  into  a small  ob- 
long ganglion  of  five  or  six  lines  long  which  extends  itself 
as  far  as  the  foramen  Iacerum.* 

Its  general  distribution  is  to  the  tongue  and  to  the  plia- 
rynx,  as  its  name  implies. 

The  three  last  nerves  have  been  erroneously  considered 
as  but  one,  probably  in  consequence  of  their  going  out  of 

* Tliis  ganglion  is  described  by  Andersech  and  by  Huber,  but  its  exist- 
ence  is  questioned  by  Bichat. 


374 


NERVOUS  SYSTEM. 


the  cranium  together,  and  of  their  being  placed  so  near  each 
other  in  this  cavity.  A very  genera!  name  for  them  coUect 
lively  has  been  that  of  the  Eighth  Pair. 

The  Auditory  Nerve  {Nervus  Jluditorius; — tdcusHcus; 
— Portlo  Mollis)  arises  in  part  from  the  medullary  strise 
on  the  surface  of  the  calamus  scriptorius,  and  partly  from 
the  corpus  restiforme,  between  the  glosso-pharyngeal  nerve, 
and  the  tuber  annulare.  At  its  origin  it  is  so  extremely 
soft  as  not  to  bear  handling,  and  is  too  pulpy  to  present  the 
appearance  of  fibres;  but  becoming  more  distant  from  the 
medulla  oblongata,  it  is  harder  and  fibrous. 

This  nerve  is  impressed  on  its  internal  face  by  a longitu- 
dinal furrow  for  the  reception  of  the  facial  nerve.  It 
passes  obliquely  forwards  and  outwards  beneath  the  crus  ce- 
rebelli,  and  penetrates  into  the  meatus  auditorius  internus. 
It  adheres  somewhat  near  its  root  to  the  under  anterior  mar- 
gin of  the  cerebellum,  just  behind  the  crus  of  the  latter;  the 
circumstance  is  considered  by  J.  F.  Meckel,  as  a proof  of 
its  having  there  another  origin,  whereby  an  analogy  is  es- 
tablished between  it  and  the  two  other  nerves  of  the  senses, 
to  wit,  the  optic  and  the  olfactory. 

The  distribution  of  this  nerve  is  confined  to  the  labyrinth 
of  the  ear. 

The  Facial  Nerve  {Nervus  Facialis,  Portio  Dura  Sep- 
timi.  Par  Septimum)  is  placed  in  front  of  and  above  the 
auditory  nerve.  It  arises  by  two  branches,  which  are  per- 
fectly distinct  from  each  other  and  difl'er  much  in  their 
size.  The  larger  one,  which  is  placed  within  and  above  the 
other,  arises  from  the  medulla  oblongata  at  the  most  supe- 
rior part  of  the  corpus  restiforme,  where  the  latter  runs  into 
the  tuber  annulare.  The  origin  of  the  perve  is  sometimes 
overlapped  by  the  latter,  so  that  some  few  of  its  fibres  ap- 
pear to  come  from  the  annular  protuberance,  while  they 
only  pass  through  it,  in  their  course  from  the  medulla  ob- 
longata. The  second  branch,  which  is  much  smaller  than 
the  other,  arises,  by  three  or  four  filaments,  from  that  por- 


2SIERVES  OP  THE  ENCEPHALON. 


375 


tion  of  the  medulla  oblongata  which  is  placed  between  the 
first  branch  and'  the  auditory  nerve. 

The  two  branches  of  the  facial  nerve  are  kept  distinct  for 
the  distance  of  several  lines  before  they  unite.  Proceed- 
ing outwards  and  backwar.d's,  they  reach  the  meatus  audito- 
rius  internus,  and  then  proceed,  as  a single  cylindrical  trunk, 
through -the  aqueduct  of  Fallopius,  to  emerge  at  the  stylo- 
mastoid foramen,  for  the  purpose  of  being  distributed  upon 
the  muscles  and  skin  of  the  head. 

The  auditory  nerve  and  the  facial  compose  the  seventh 
pair  of  writers.. 

The  Sixth  Pair  of  Nerves  {Par  Sextum^  Motor  Oculi 
Externus)  is  found  four  or  five  lines  distant  from  the  facial 
nerve,  and  at  its  internal  side.  It  arises  from  the  base  or 
upper  extremity  of  the  corpus  pyramidale,  under  the  pos- 
terior margin  of  the  tuber  annulare;  when  the  latter  is 
broader  than  usual,  some  of  the  fibres  seem  to  come  from 
it;  but  the  appearance  is  deceptious,  as  they  only  penetrate 
it.  The  fibres  are  assembled  into  two  roots,  of  which  the 
internal  is  three  or  four  times  as  large  as  the  other. 

These  roots,  before  they  penetrate  the  dura  mater,  most 
commonly  unite  into  a single  trunk,  which  goes  almost  di- 
rectly forwards,  and  is  enveloped  in  a neurileme.  Passing 
through  the  cavernous  sinus,  it  gets  into  the  orbit  by  the 
sphenoidal  fissure,  and  is  spent  upon  the  abductor  oculi 
muscle. 

The  Nefvus  Trigeminus  (also  called  Tnyh^'a/,  ParQuin- 
tiim)  is  one  of  the  largest  among  those  that  proceed  from 
the  basis  of  the  brain,  and  emerges  from  the  side  of  the 
pons  varolii,  just  where  it  is  continuous  with  the  crus  ce- 
rebelli.  It  is  composed  of  three  roots:  an  anterior,  a pos- 
terior, and  a middle;*  of  which  the  latter  is  much  the 
largest. 

The  Middle  Root  is  about  a line  and  a half  in  breadth, 

* Santorini,  Observ.  Anat.  Venitia,  1724.  Soeinmering’,  de  Corp.  Him). 
Fabrica,  tom.  iv.  Gall  and  Spurzheim,  Anat.  Du.  Cerv. 


NERVOUS  SYSTEM. 


av6 

and  has  a passage  made  for  it  by  the  very  obvious  splitting 
of  the  superficial  fibres  of  the  ponsvarolii.  It  is  composed 
of  thirty  or  forty  fasciculi,  which  are  divisible  into  a hun- 
dred or  more  fibres.  These  fasciculi  may  be  traced  into 
the  substance  of  the  tuber  annulare,  (but  intersected  by  the 
transverse  fibres  of  the  latter,)  in  the  direction  of  the  fourth 
ventricle.  When  they  have  come  near  the  latter,  they  may 
be  traced  thence  into  the  medulla  oblongata,  towards  the 
fissure  that  exists  between  the  corpus  olivare  and  restiforme. 
It  is  at  this  point,  that  the  greater  number  of  the  fibres 
arise;  some  from  the  corpus  olivare,  and  others  from  the  fis- 
sure. 

The  commencement  of  this  root  is  pulpy  and  destitute  of 
fibres,  and  is  surrounded  by  grayish  substance;  but  when 
it  has  advanced  into  the  pons,  it  is  surrounded  by  a fine': 
membrane,  and  is  very  evidently  fibrous.  There  is  a suc- 
cessive increase  in  its  size,  from  its  commencement  till  it 
is  ready  to  emerge  from  the  pons,  when  it  becomes  some- 
what contracted,  and  immediately  afterwards  increases  again 
considerably  in  size.  It  then  enters  a canal  of  the  dura 
mater  at  the  fore  part  of  the  petrous  portion  of  the  tempo- 
ral bone,  and  just  behind  the  cavernous  sinus.  This  canal 
sets  but,  loosely  about  it  at  first,  but  afterwards  it  adheres  to 
the  surface  of  the  nerve. 

The  middle  root  of  the  nervus  trigeminus,  in  the  upper 
part  of  the  canal  of  the  dura  mater,  preserves  its  fasciculated 
appearance,  and  many  small  filaments  are  interchanged  be- 
tween the  fasciculi,  so  as  to  make  a complex  net-work.  But 
at  the  lower  part  of  the  canal,  in  the  dura  mater,  it  is  con- 
verted into  a ganglion  of  a semilunar  shape,  with  its  concavi- 
ty upwards,  having  about  six  or  eight  lines  in  length,  and 
one  and  a half  in  breadth.  This  body,  (called  the  Ganglion 
of  Meckel,  Ganglion  Semilunare,  Plexus  Gangliformis)  is 
compact,  and  has  its  fibres  very  much  matted  above,  but  be- 
low they  assemble  into  larger  and  more  distinct  fasciculi, 
which  are  afterwards  arranged  into  three  principal  trunks, 
departing  from  the  cranium  through  different  foramina;  to 


NERVES  OF  THE  ENCEPHALON. 


377 


wit,  through  the  sphenoidal  fissure,  the  foramen  rotundum, 
and  the  foramen  ovale. 

J.  F.  Meckel  asserts  that  the  filaments  of  the  plexus  above 
the  ganglion,  for  the  most  part  terminate  in  a gutter  formed 
in  the  superior  margin  of  the  ganglion,  and  that  there  are 
but  very'few  of  them  which  can  be  traced  into  the  trunks 
below.  The  trunks  below  consequently  arise  from  the  cir- 
cumference of  the  ganglion. 

The  two  smaller  roots  of  the  nervus  trigeminus  proceed 
out  of  the  tuber  annulare  at  different  points,  from  that  of  the 
large  root,  and  each  one  has  its  appropriate  fissure  for  that 
purpose.  One,  from  its  situation,  is  called  Anterior,  and 
the  other  Posterior.  Each  may  be  traced  into  the  posterior 
cord  of  the  medulla  oblongata,  but  not  so  far  as  the  large 
middle  root,  and  is  formed  by  several  fasciculi  of  medullary 
fibres.  The  Anterior  and  the  Posterior  roots,  after  going 
separately  for  six  or  eight  lines,  unite  to  form  a single  cord. 
This  cord  does  not  merge  itself  in  the  semilunar  ganglion, 
but  continues  distinct  from  it*  with  the  exception  of  send- 
ing off  to  it  a few  fibres,  it  afterwards  gets  from  the  cranium 
through  the  foramen  rotundum,  and  is  distributed  to  some 
of  the  muscles  of  mastication,  as  the  temporal  and  bucci- 
nator. 

The  general  distribution  of  the  fifth  pair  of  nerves,  or 
the  trigeminus,  is  to  the  orbit,  to  the  face,  and  to  the 
tongue. 

The  Pathetic  Nerve  {Nervus  Patheticus,  Par  Cerebrals 
Quartuum,  Fourth  Pair)  is  the  smallest  which  comes  from 
the  encephalon,  and  is  not  larger  than  a sewing  thread.  It 
arises  by  two  filaments  or  roots  from  the  upper  anterior  face 
of  the  valve  of  the  brain,  just  below  the  testes.  This  ori- 
gin is  soft,  and  easily  broken  from  the  want  of  aneurileme, 
but  the  latter  is  soon  afterwards  furnished. 

The  nervus  patheticus  appears  on  the  base  of  the  brain, 
between  the  cerebellum  and  the  posterior  lobes  of  the  cere- 
brum, at  the  external  margin  of  the  tuber  annulare.  It 

* In  this  respect  the  fifth  pair  resembles  one  of  the  spinal  nerves. 

VoL.  II, — 48 


376 


NKRVOUS  SYSTEM. 


then  goes  for  some  distance  along  the  margin  of  the  tento- 
rium till  it  comes  near  the  posterior  clinoid  process;  it  then 
penetrates  into  a canal  of  the  dura  mater,  and  reaches  the 
orbit  of  the  eye  througli  the  sphenoidal  fissure,  to  be  dis- 
tributed on  the  superior  oblique  muscle. 

The  Third  Pair  {Par  Tertium,  Nervus  Motor  Oculi) 
arises  fi'om  the  internal  face  of  the  crus  cerebri,  about  two 
lines  in  advance  of  the  anterior  margin  of  the  tuber  annu- 
lare. Its  roots  come  in  great  part  from  the  cineritious  mat- 
ter which  is  found  on  this  surface  of  the  crus,  and  may  be 
traced  for  some  distance  upwards  and  backwards  along  the 
parietes  of  the  third  ventricle.  The  nerves  of  the  opposite 
sides  are  in  contact  for  some  distance  by  the  internal  faces 
of  their  roots,  but  do  not  adhere. 

The  Nervus  Motor  Oculi  proceeds  from  its  origins  to- 
wards the  external  margin  of  the  cavernous  sinus,  and  pe- 
netrating into  the  orbit  through  the  sphenoidal  fissure,  it  is 
distributed  to  most  of  the  muscles  of  the  eyeball. 

The  Optic  Nerve  {Nervus  Opticus,  Par  Secundu7n)'\5 
about  the  same  size  with  the  trigeminus.  It  arises  by  a 
broad  flattened  root,  one  portion  of  which  comes  from  the 
posterior  end  of  the  thalamus  opticus,  and  another  from  the 
testis  through  the  means  of  a medullary  band  that  passes 
from  the  latter  towards  the  thalamus  of  the  same  side.  From 
this  point  the  optic  nerve  winds  forwards  under  the  crus  ce- 
rebri, adhering  to  it,  and  inclining  inwards  towards  its  fel- 
low. Its  adhesion  to  the  crus  is  considered  by  many  ana- 
tomists as  another  of  its  origins. 

The  Optic  Nerve  having  reached  the  under  anterior  part 
of  the  third  ventricle,  adheres  so  closely  to  its  fellow  that  the 
two  seem  fused  together,  in  such  a way  that  there  is  no  line 
of  separation  between  them.  This  junction  receives  above, 
from  the  third  ventricle,  some  medullary  filaments,  which 
Meckel  feels  authorized  to  consider  as  another  origin.  The 
junction  presents  the  form  of  the  letter  X,  and  is  called  the 
chiasm  or  crossing  of  the  optic  nerves.  The  most  distin- 
guished anatomists,  however,  have  laboured  in  vain  to  set- 


NERVES  OF  THE  ENCEPHALON. 


379 


tie  the  question  of  this  mode  of  junction;  some  believing 
that  there  was  only  a lateral  union,  others  that  the  nerve  of 
one  side  crossed  over  to  the  other  side,  and  others,  again, 
that  the  decussation  occurred  only  with  some  of  the  fibres, 
but  not  all.  Observations,  in  comparative  anatomy,  on  blind- 
ness, and  indeed  on  every  conceived  mode  of  elucidation, 
have  been  resorted  to  without  producing  a solution  of  the 
problem;  but  the  discussion  of  their  merits  would  require 
too  much  space  for  the  present  work. 

The  Optic  Nerves  as  they  approach  their  chiasm  become 
more  cylindrical,  and  continuing  so  afterwards,  penetrate 
into  the  orbits  through  the  foramina  optica.  It  is  only  in 
front  of  their  junction  that  they  are  invested  by  a neurileme, 
which,  having  considerable  firmness,  penetrates  into  their 
interior  and  divides  them  into  distinct  canals. 

The  Olfactory  Nerve  {Nervus  Olfactorius,  Par  Pri- 
mufri)  is  situated  on  the  under  surface  of  the  anterior  lobes 
of  the  brain,  near  the  fissure  that  separates  the  hemispheres. 
It  goes  forwards  from  its  root,  and  also  converges  gradual- 
ly towards  its  fellow,  so  as  to  reach  the  cribriform  plate  of 
the  ethmoid  bone,  through  the  perforations  of  which  it 
passes  out.  In  its  coui’se,  it  is  lodged  in  a small  furrow, by 
which  pressure  upon  it  is  prevented. 

This  nerve  arises  by  three  medullary  fasciculi,  or  roots, 
from  the  basis  of  the  brain  at  the  corpus  striatum,  in  the  fis- 
sure of  Sylvius,  where  the  anterior  and  posterior  lobes  join 
each  other;  these  roots  are  from  eight  to  twelve  lines  on 
the  outer  side  of  the  infundibulum.  The  roots  are  placed, 
in  regard  to  each  other,  diverging;  one  is  within,  another 
in  the  middle,  and  the  third  external.  The  external  root 
is  the  longest,  and  arises  from  the  extreme  posterior  mar- 
gin of  the  anterior  lobe  by  its  last  convolution.  It  has  a 
curved  course  from  without  inwards,  the  concavity  of  which 
is  forwards  and  the  convexity  backwards.  The  internal 
root  is  concealed  by  the  chiasm  of  the  optic  nerves,  and 
arises  from  the  adjacent  surface  of  the  anterior  lobe.  The 
middle  root  comes  from  the  posterior  margin  of  the  anterior 
lobe  by  the  cribriform  surface,  which  is  between  the  other 


380 


MKHVOUS  SYSTKM. 


two  roots.  These  origins  unite  to  form  a single  prismatic 
cord,  which  increases  in  size  as  it  advances  forwards,  and 
consists  of  medullary  and  cineritious  longitudinal  fibres 
mixed  together. 

The  anterior  extremity  of  the  olfactory  nerve  is  swollen 
out  into  what  is  called  the  bulb,  {Bnlbus)  and  sends  from 
its  under  surface  filaments,  which,  surrounding  themselves 
with  a tunic  from  the  dura  mater,  penetrate  into  the  nose 
and  spread  themseh^es  on  the  Schneiderian  membrane.  In 
its  whole  length  it  is  exceedingly  soft  and  pulpy,  till  it 
gets  out  of  the  cranium. 


SECT.  VII. — OF  THE  ARTERIES  OF  THE  BRAIN. 

The  arteries  of  the  brain,  or  pia  mater,  are  derived  from 
the  two  internal  carotids,  and  from  the  two  vertebrals. 

The  Internal  Carotid  Artery  {Carotis  Interna)  gets  into 
the  cavity  of  the  cranium  through  the  carotid  canal  of  the 
temporal  bone,  conforming  itself  of  course  to  the  curvature 
of  this  canal,  and  being  brought  by  it  to  the  posterior  part 
of  the  body  of  the  sphenoidal  bone.  In  escaping  from  the 
petrous  bone  it  has  to  ascend,  and  also  to  advance  some- 
what, by  which  it  is  brought  to  the  posterior  part  of  the 
sella  turcica.  From  this  point  it  goes  horizontally  forwards 
through  the  cavernous  sinus,  and  reaching  its  fore  part,  it 
then  ascends  again,  and  goes  towards  the  fissure  of  Sylvius. 
While  in  the  carotid  canal,  it  gives  a small  branch  to  the 
tympanum  of  the  ear,  and  as  it  lies  on  the  side  of  the  sella 
turcica  it  gives  off  the  anterior  and  the  posterior  arteries  of 
the  cavernous  sinus.  When  i*  reaches  the  anterior  clinoid 
process  it  sends  off  a large  branch  through  the  optic  fora- 
men to  the  parts  contained  within  the  orbit  of  the  eye. 
This  branch  is  the  ophthalmic  artery,  and  what  remains  of 
the  internal  carotid  is  then  distributed  to  the  brain  after  the 
following  order. 

There  are,  first  of  all,  some  small  branches  sent  to  the 


ARTERIES  OF  THE  ENCEPHALON. 


381 


adjacent  parts,  as  the  pituitary  gland,  the  infundibulum, 
and  the  lower  part  of  the  third  ventricle. 

The  Arteria  Communicans  Posterior  is  directed  back- 
wards and  inwards,  and  runs  into  the  corresponding  trunk 
of  the  basilar  artery  called  the  posterior  cerebral.  There 
are  some  varieties  in  regard  to  the  size  and  precise  point  of 
origin  of  this  trunk,  which  it  would  be  needless  to  mention 
particularly.  Besides  the  important  anastomosis  formed  by 
it,  it  detaches  several  ramuseles  to  the  adjacent  parts  of  the 
pia  mater. 

The  Arteria  Choroidea  is  the  next  branch  from  the  inter- 
nal carotid.  It  goes  outwards  and  backwards,  and  after  de- 
taching some  minor  branches,  it  penetrates  into  the  inferior 
cornu  of  the  lateral  ventricle,  by  the  side  of  the  Pons  Va- 
rolii,  and  expends  itself  in  ramifications  upon  the  plexus 
choroides. 

The  Arteria  Callosa,  or  Anterior  Cerebri,  is  detached  from 
the  internal  carotid,  opposite  the  last.  It  advances  in  front 
of  the  union  of  the  optic  nerves,  converging  rapidly  at  the 
same  time  towards  its  fellow.  Just  before  the  chiasm  of  the 
optic  nerves,  a transverse  branch  passes  between  it  and  its 
fellow.  This  branch,  the  Arteria  Communicans  Anterior, 
is  of  variable  length  and  size  in  different  subjects,  being 
sometimes  a line,  and  on  other  occasions  three  or  four  lines 
long. 

The  arteria  callosa  then  keeps  near  its  fellow  on  the  under 
surface  of  the  hemisphere,  giving  out  small  branches;  and 
having  got  on  a line  with  the  anterior  margin  of  the  corpus 
callosum,  it  ascends  on  the  flat  side  of  the  hemisphere,  and 
divides  into  anterior  and  into  posterior  twigs.  The  former 
supply  the  fore  flat  part  of  the  hemisphere,  the  latter  the 
corpus  callosum  and  the  adjacent  surface  of  the  brain. 
These  several  branches  of  the  arteria  anterior  reach  as  far 
as  the  upper  convex  surface  of  the  brain,  and  there  anas- 
tomose with  other  arteries. 

The  Internal  Carotid  may  now  be  considered  to  have  lost 
its  name,  and  the  trunk  is  continued  as  Arteria  Cerebri  Me- 
dia. It  is  directed  outwards,  and  engages  in  the  fissure  of 


3S2 


NERVOUS  SYSTEM. 


Sylvius;  while  there  it  detaches  a great  number  of  branches 
to  the  ad  joining  surfaces  of  the  anterior  and  of  the  middle 
lobes.  Some  of  these  branches  are  of  considerable  magni- 
tude, and  winding  along  the  convolutions  of  the  brain,  they 
at  length  ascend  to  the  upper  surface  of  the  hemisphere, 
and  anastomose  with  the  branches  of  the  anterior  and  of  the 
posterior  cerebral  artery. 

The  Vertebral  Artei;y  {Jirteria  Vertebralis)  is  a branch 
of  the  subclavian.  In  order  to  reach  the  cavity  of  the  cra- 
nium it  has  to  traverse  the  foramina  of  the  transverse  pro- 
cesses of  the  six  upper  vertebrae  of  the  neck.  It  ascends 
in  a straight  tine  till  it  reaches  the  second  vertebra,  but 
there,  in  order  to  pass  through  the  transverse  process,  it 
takes  a direction  upwards  and  outwards.  It  then  ascends 
vertically  again  till  it  has  passed  through  the  transverse 
process  of  the  first  vertebra.  After  which  it  takes  a hori- 
zontal course  winding  around  the  posterior  face  of  the  up- 
per oblique  process  of  the  same  vertebra,  in  a depression 
for  the  purpose,  and  having  reached  the  internal  extremity 
of  this  process,  it  ascends  upwards  and  inwards  through  the 
occipital  foramen  into  the  cavity  of  the  cranium;  perfora- 
ting the  dura  mater  just  above  the  condyle  of  the  occipi- 
tal bone.  Having  got  into  the  cranium,  it  is  first  on  the 
side  and  then  on  the  under  surface  of  the  medulla  oblonga- 
ta, and  continues  to  approach  its  fellow  till  it  reaches  the 
posterior  margin  of  the  tuber  annulare.  At  this  point  the 
two  vertebral  arteries  coalesce,  and  from  their  union  results 
the  basilar  artery. 

The  vertebral  artery  in  this  course,  from  its  origin  to  its 
termination,  detaches  several  arterioles  to  the  heads  of  the 
adjoining  muscles,  to,  the  membranes  of  the  spinal  marrow, 
and  to  the  nerves  as  they  come  out  of  the  intervertebral  fo- 
ramina; they  are  generally  too  small  and  irregular  to  de- 
serve a special  description.  At  its  upper  extremity,  how- 
ever, it  sends  off  three  branches  of  some  consequence;  the 
Spinalis  Posterior;  the  Spinalis  Anterior;*  and  the  Inferior 
Cerebelli. 


* See  Arteries  of  Medulla  Spinalia. 


ARTERIES  OF  THE  ENCEPHALON.  383 

The  Arteria  Inferior  Cerebelli,  divides  shortly  after  its 
origin,  or  otherwise  is  double  from  the  beginning.  The 
most  posterior  trunk  is  distributed  about  the  bottom  of  the 
fourth  ventricle,  on  the  fundamental  portion  of  the  cerebel- 
lum, and  the  contiguous  faces  of  the  two  hemispheres  or 
lobes  of  the  latter.  The  other  trunk  of  this  artery  is  dis- 
tributed on  the  under  surface  of  the  cerebellum. 

The  Basilar  Artery  {Arteria  Basilaris)  is  on  the  middle 
line  of  the  tuber  annulare,  and  extends  from  its  posterior  to 
its  anterior  margin.  In  this  course  it  detaches  some  arte- 
rioles to  the  tuber;  others  to  the  meatus  auditorius  internus, 
{Arterise  Auditivse  Internse)  which  are  spent  upon  the  la- 
byrinth, and  anastomose  with  twigs  from  the  internal  and 
external  carotids.  At  its  anterior  extremity  it  detaches  on 
each  side  two  considerable  trunks;  first,  the  superior  artery 
of  the  cerebellum,  and  immediately  afterwards  the  poste- 
rior artery  of  the  cerebrum. 

The  Arteria  Superior  Cerebelli  goes  outwardly  from  its 
origin  just  behind  the  anterior  edge  of  the  tuber  annulare, 
until  it  gains  the  front  margin  of  the  cerebellum.  It  then 
divides  into  several  branches,  some  of  which  are  distributed 
on  the  upper  surface  of  the  cerebellum  and  run  to  its  poste- 
rior margin,  where  they  anastomose  with  the  branches  of 
the  arteria  inferior;  others  are  spent  upon  the  substance  of 
the  cerebellum  near  its  anterior  edge. 

The  Posterior  Artery  of  the  Cerebrum  {Arteria  Cerebri 
Posterior)  one  on  each  side,  is  the  termination  of  the  ba- 
silar artery.  It  proceeds  abruptly  outwards,  and  has  gone 
but  a few  lines  when  it  receives  the  arteria  communicans 
posterior  of  the  internal  carotid.  It  then  continues  out- 
wardly parallel  with  the  anterior  margin  of  the  tuber  annu- 
lare, and  near  it  crosses  the  crus  cerebri,  and  is  then  distri- 
buted on  the  inferior,  and  on  the  posterior  part  of  the 
hemisphere,  and  of  the  corpus  callosum.  As  mentioned, 
its  branches  anastomose  with  those  of  the  anterior  and  of 
the  middle  arteries. 


It  will  now  be  understood,  that  an  arterial  circle  encloses 


3S4 


NERVOUS  SYSTEM. 


the  chiasm  of  the  optic  nerves  and  the  corpora  albicantia. 
The  fore  and  lateral  parts  of  the  circle  are  formed  by  the 
internal  carotids  and  their  branches,  while  the  hind  part  is 
formed  by  the  Basilar  Artery  and  its  bifurcation.  This  is 
the  circle  of  Willis,  and  establishes  a very  free  communi- 
cation between  the  vessels  of  the  two  sides  of  the  brain. 


The  veins  of  the  Brain  have  been  sufficiently  alluded  to 
in  the  account  of  the  Pia  Mater,  and  of  the  Sinuses  of  the 
Dura  Mater. 


BOOK  IX. 


PART  III. 

Senses. 

To  the  peripheral  portion  of  the  nervous  system,  belong 
all  the  nerves  which  are  sent  off  from  the  Medulla  Spinalis 
and  Encephalon,  as  well  as  the  Sympathetic.  Some  of  these 
nerves  have  a special  apparatus  attached  to-  their  external 
extremities,  for  the  purpose  of  augmenting  and  facilitating 
their  appropriate  powers  of  sensation;  of  this  class  are  the 
Optic,  the  Olfactory,  and  the  Auditory.  Others  of  them,  as 
the  nerves  of  the  tongue  and  of  the  skin,  though  they  are 
the  means  of  special  sensations,  yet  the  apparatus  upon 
which  they  are  spread  is  applied  to  many  purposes,  more 
striking  and  useful,  than  that  of  indicating  the  presence  of 
surrounding  bodies.  And  lastly,  the  remaining  nerves 
being  by  far  the  most  numerous  and  large,  are  distributed 
to  the  muscles  and  to  the  viscera. 


CHAPTER  L 

OF  THE  EYE  AND  OF  ITS  DEPENDENCIES. 

The  organ  of  vision,  which  depends  upon  the  optic  nerve 
for  its  usefulness,  is  formed  by  the  Ball  of  the  Eye  and 
many  Dependencies  or  Auxiliary  parts,  all  of  which  are  si- 
tuated within  the  orbit,  and  fill  up  its  cavity. 

VoL.  II. — -49 


NJillVOUS  SYSTJiJU. 


SECT.  I. OF  THE  AUXILIARY  PARTS  OF  THE  EYE.  - 

The  Eyelids  [Palpehrae)  are  placed  at  the  anterior  orifice 
of  the  orbit,  and  serve  to  shut  out,  by  their  closing,  the  light 
from  the  eye,  and  also,  by  their  frequent  motions,  to  sweep 
the  front  of  the  eyeball,  so  as  to  remove,  from  its  transpa- 
I’ent  part,  moats  and  dust.  They  are  distinguished  into 
upper  and  lower,  and  the  place,  at  each  end,  where  the 
horizontal  fissure  between  them  ceases,  is  called  their  Com- 
missure, Angle,  or  Canthus.  The  angle  next  to  the  nose,  or 
the  internal,  is  called  the  Great  one,  and  the  other,  the 
Litte  one. 

The  Internal  Canthus  is  united  to  the  nasal  process  of  the 
superior  maxillary  bone  by  a rounded  tendon  [Ligamen- 
tum  Palpebrale  Internum,)  which  passes  horizontally  in- 
wards, and  is  nearly  half  an  inch  in  length.  It  throws  the 
skin  into  a small  ridge,  which  may  be  distinctly  seen  and 
felt  at  tjiis  point.  The  External  Canthus  is  held  in  place  by 
its  general  attachments  of  cellular  substance  and  by  the  ex- 
ternal palpebral  ligament. 

The  upper  eyelid  is  somewhat  larger  than’the  lower,  but 
the  structure  of  both  is  the  same,  for  each  one  is  formed  bj^ 
skin  externally;  next  to  it  a plane  of  muscular  fibres,  being 
the  orbicularis  palpebrarum;  then  a plate  of  cartilage,  and 
lastly,  a thin  membrane  uniting  it  to  the  eyeball. 

There  is  nothing  in  the  texture  of  the  skin  of  the  eyelid 
which  needs  description  in  a more  particular  manner,  than 
that  of  stating  its  fineness,  its  thinness,  the  looseness  of  its 
attachment  to  the  muscle  beneath  by  long  yielding  cellular 
substance,  and  the  deficiency  of  adipose  matter.  It  is  ren- 
dered prominent  at  the  superior  margin  of  the  orbit,  both 
by  the  projection  of  the  bone  there,  and  by  the  presence  of 
the  corrugator  supercilii  muscle  at  its  internal  extremity. 
This  prominence  is  furnished  with  an  arched  cluster  of 
hairs,  {Supercilia,)  which  have  their  loose  ends  inclined 
horizontally  outwards,  and  are  rather  more  abundant  at  the 
root  of  the  nose  than  externally.  The  supercilia  of  the  two 


EY£. 


387 


sides  are  separated  commonly  by  a smalt  bai’e  space  called 
Glabella,  the  existence  of  which  adds  much  to  the  calm  and 
intellectual  expression  of  the  human  countenance;  whereas 
the  junction  of  the  two  eyebrows,  by  the  hairs  filling  up 
this  space,  gives  a gloomy,  and  occasionally  a ferocious  ap- 
pearance. 

The  margins  of  the  eyelids  are  also  furnished  with  hairs, 
(Cilia,)  the  roots  of  which  are  insinuated  between  the  skin 
and  the  tarsus  cartilage.  The  hairs  of  the  upper  lid  are 
longer  and  more  numerous  than  those  of  the  lower;  they 
are  concave  upwards,  while  the  latter  are  concave  down- 
wards, so  that  the ’convexities  of  the  two  ranges  of  hairs 
come  in  contact  when  the  eyelids  are  closed.  The  hairs  of 
each  cilium  are  disposed  into  three  or  four  rows,  by  which 
a long  brush  is  formed,  the  central  hairs  of  which  are  longer 
and  larger  than  any  others. 

The  hairs  of  the  supercilia  and  of  the  cilia  resemble  one 
another  strongly,  for  when  examined  closely  each  one  will  * 
be  found  to  have  a bulbous  soft  rootj  just  beyond  which 
there  is  a narrow  part.  The  middle  of  the  hair  is  swollen, 
and  its  external  extremity  is  brought  to  a fine  point.  These 
hairs  correspond  in  colour  with  the  hairs  of  the  head. 

When  the  orbicularis  muscle  is  removed,  a ligaiuentous 
■or  fibrous  membrane  is  found  passing  from  the  external  mar- 
gin of  the  orbit  to  the  corresponding  margin  of  the  palpe- 
bral cartilages,  and  separating  the  eyelids  from  the  parts 
contained  within  the  orbit.  There  is  a partial  decussation 
of  the  fibres  of  this  membrane,  from  the  external  commissure 
of  the  cartilages  to  the  external  edge  of  the  orbit;  it  has 
more  firmness  than  any  other  part  of  the  membrane,  and  is 
the  external  palpebral  ligament,  (Ligamentum  Palpebralc 
Externum. ) On  the  side  of  the  internal  canthus  of  the  orbit 
there  is  no  corresponding  ligamentous  expansion,  but  a few 
irregular  fibres,  which  allow  the  masses  of  fat  beneath  to 
project  forwards  betwefen  their  fasciculi. 

The  Palpebral  Cartilages  ( Tarsi)  are  two  in  number,  one 
at  the  margin  of  each  eyelid,  to  which  they  communicate  a 


S88 


NERVOUS  SYSTEM. 


smooth,  even  surface  from  the  internal  to  the  external  com- 
missure. They  are  between  the  orbicularis  muscle  and  the 
tunica  conjunctiva.  The  upper  one  is  larger  than  the  lower, 
resembles  an  oval  cut  in  half  in  its  long  diameter,  and  is 
about  six  lines  broad  in  its  middle;  the  lower  one  is  of  a 
breadth,  nearly  uniform  of  about  two  lines.  Their  internal 
extremities  cease  just  before  they  reach  the  puncta  lachry- 
malia,  and  are  connected  with  the  internal  palpebral  liga- 
ment, which  has  been  described  as  one  of  the  origins  of  the 
orbicularis  oculi  muscle  connecting  it  with  the  nasal  process 
of  the  upper  maxillary  bone;  their  external  extremities 
ce^se  just  before  their  commissure,  and  are  firmly  attached 
to  the  external  palpebral  ligament. 

These  cartilages  are  thicker  where  they  form  the  margin 
of  the  eyelids,  and  have  there  a slope  or  bevel,  by  which 
when  in  contact,  a small  groove  is  formed  on  their  posterior 
surface.  From  their  resistance  to  the  concentric  contrac- 
tions of  the  orbicularis,  they  keep  the  eyelid  smooth  and 
favour  its  sliding  upon  the  eyeball.  Certain  animals,  being 
destitute  of  these  cartilages,  when  they  wink,  the  skin  by 
the  contraction  of  the  orbicularis,  is  drawn  up  like  the  mouth 
of  a purse. 

Conjunctiva. — Below  the  palpebral  cartilages  is  the  fourth 
layer  of  the  eyelid,  the  conjunctiva.  It  is  white,  thin,  and 
diaphanous,  in  the  uninflamed  state.  Beginning  at  the  roots 
of  the  cilia,  where  it  is  continuous  with  the  skin,  it  covers 
the  posterior  face  of  each  eyelid,  is  reflected  for  eight  or 
ten  lines  towards  the  bottom  of  the  orbit,  and  then  passes 
to  the  eyeball,  of  which  it  covers  the  anterior  half,  not  ex- 
cepting the  cornea.  It  penetrates  into  the  lachrymal  ducts, 
to  be  continuous  with  the  lining  membrane  of  the  lachrymal 
sac. 

From  this  description,  it  is  evident  that  the  tunica  con- 
junctiva has  one  surface  presented  against  itself  when  the 
eyelids  are  closed ; this  surface  is  lubricated  and  very  smooth, 
so  as  to  permit  a free  motion  of  the  lids  and  ball  of  the  eye. 
The  other  surface  is  connected  in  its  anterior  half  by  cellu- 
lar substance  to  the  eyelids,  and  in  its  remaining  part  to  the 


EYE. 


389 


ball  of  the  eye,  by  the  same  means.  It  is  united  rather 
loosely  to  the  sclerotica  till  it  gets  near  the  margin  of  the 
cornea;  but  to  the  latter  it  adheres  so  firmly,  and  changes 
there  so  much  its  own  texture,  that  it  seems  like  a portion 
of  the  cornea. 

This  membrane,  from  its -continuity  with  the  skin  and  the 
lining  membrane  of  the  nose,  from  its  sympathies  with  them, 
from  the  nature  of  the  discharge  from  it,  and  from  its  ex- 
treme sensibility,  is  ranked  by  Bichat  among  the  mucous 
membranes.  It  has,  however,  some  peculiarities  in  its 
structure,  for  it  is  entirely  .deficient  in  villosities,  and  though 
most  abundantly  furnished  with  capillary  vessels,  they  do 
not  admit  red  blood,  but  in  a state  of  irritation. 

Glandule  Palpebrarum. — These  bodies,  also  called  the 
glands  of  Meibomius,  from  an  anatomist  who  has  described 
them  particularly,  are  situated  at  the  margin  of  each  eyelid, 
between  its  cartilage  and  the  conjunctiva.  They  are  about 
two  or  three  lines  long,  and  appear  like  small,  white,  ser- 
pentine threads,  running  at  right  angles  to  the  margin  of 
the  lid,  near  to,  and  parallel  with  one  another.  They  are 
more  abundant  on  the  upper  than  on  the  lower  lid.  They 
terminate  by  a row  of  small  orifices  in  the  margin  of  the  lid 
just  behind  the  cilia.  For  preventing  the  overflowing  of  the 
tears,  and  the  sticking  together  of  the  eyelids,  they  dis- 
charge an  unctuous  fluid,  which  may  be  made  manifest  by 
squeezing  them.  Their  secretion  is  occasionally  much  aug- 
mented, and  then  has  a large  quantity  of  serum  and  glu- 
tinous matter  in  it;  in  this  case  the  evaporation  of  the  serum 
makes  it  adhesive,  and  causes  the  eyelids  to  adhere  after 
they  have  been  closed  for  some  time,  as  in  sleep. 

The  Musculus  Levator  Palpebrse  Superioris  is  placed  in 
the  superior  part  of  the  orbit.  It  arises  by  a small  round 
tendon  from  the  upper  margin  of  the  optic  foramen,  and  be- 
coming fleshy,  it  expands  itself  into  a long  thin  triangle,  of 
which  the  base  is  in  front.  It  covers  the  rectus  superior 
muscle. 

Terminating  in  front  by  a thin  tendinous  expansion,  it  is 


390 


NERVOUS  SYSTEM. 


inserted  into  the  superior  margin  of  the  upper  palpebral  car- 
tilage; but  some  of  its  fibres  continue  on  between  the  latter 
and  the  orbicularis  to  the  lower  edge  of  the  cartilage. 

It  raises  the  upper  lid,  by  di'awing  it  towards  the  bottom 
of  the  orbit. 

Muscles  of  the  Eyeball. 

There  are  six  muscles  concerned  in  moving  the  eyeball, 
four  of  whiph,  from  their  direction,  are  said  to  be  straight; 
and  the  other  two,  for  the  same  reason,  are  called  oblique. 
With  the  exception  of,  the  inferior  oblique,  they  all  arise 
from  the  bottom  of  the  orbit. 

1.  The  Rectus  Oculi  Superior,  being  placed  immediately 
below  the  levator  palpebrEe,  arises  from  the  superior  margin 
of  the  optic  foramen,  and  from  the  contiguous  part  of  the 
optic  nerve.  It  runs  forward,  increasing  somewhat  in 
breadth,  and  is  inserted  by  a broad  thin  tendon  into  the 
sclerotica,  two  lines  from  the  cornea. 

It  turns  the  eye  upwards. 

2.  The  Rectus  Oculi  Externus  arises  from  the  external 
margin  of  the  optic  foramen.  It  then  advances  along  the 
middle  of  the  external  wall  of  the  orbit,  to  the  periosteum 
of  which  it  adheres  slightly,  and  is  finally  inserted,  by  a thin 
broad  tendon,  into  the  external  side  of  the  sclerotica,  about 
two  or  three  lines  from  the  cornea. 

It  abducts  the  eye,  or  turns  it  outwards. 

3.  The  Rectus  Oculi  Inferior  arises  also  from  the  optic 
foramen  at  its  inferior  margin,  and  lying  upon  the  floor  of 
the  orbit  as  it  advances  forwards,  it  is  inserted  tendinous 
into  the  under  surface  of  the  sclerotica,  two  lines  from  the 
cornea. 

It  depresses  the  eye,  or  turns  it  downwards, 

4.  The  Rectus  Oculi  Internus  arises  from  the  internal 
margin  of  the  optic  foramen,  and  goes  forwards  along  the 


KYi;. 


o9 1 

internal  wall  of  the  orbit,  being  separated  from  it  by  a layer 
of  adipose  matter.  It  is  inserted,  by  a tendinous  expansion, 
into  the  inner  side  of  the  sclerotica,  two  or  three  lines  from 
the  cornea. 

It  adducts  the  eye,  or  turns  it  inwards. 

/. 

5.  The  Oliquus  Oculi  Superior  is  placed  along  the  upper 
internal  angle  of  the  orbit.  It  arises  from  the  correspond- 
ing margin  of  the  optic  foramen,  by  a small  round  tendon; 
it  then  advances  forwards,  and  when  it  has  got  near  the 
margin  of  the  orbit,  it  is  converted  into  a long  round  ten- 
don.. 

The  tendon  passes  through  a cartilaginous  loop  which  is 
formed  for  it,  just  at  the  inner  margin  of  the  supra  orbitary 
foramen,  and  is  connected  to  the  loop  by  long  loose  cellular 
substance,  which  permits  it  to  play  freely  backwards  and 
forwards.  The  tendon  from  this  point  changes  its  direction 
by  going  backwards  and  outwards;  it  also  becomes  more 
flat,  and  is  then  inserted  into  the  upper  face  of  the  sclero- 
tica, near  its  middle,  just  beneath  the  internal  margin  of  the 
rectus  superior  muscle. 

This  muscle  is  the  longest,  but  the  most  delicate  of  those 
belonging  to  the  eyeball.  According  to  Soemmering,  it 
draws  the  eyeball  forwards,  and  towards  the  internal  can- 
thus,  and  directs  the  pupil  towards  the  cheek.  By  the  aid 
of  the  inferior  oblique,  it  draws  the  eyeball  towards  the 
nose:  it  expresses  pride:  it  appears  to  be  greatly  .excited  in 
anger.* 

The  precedina;  muscles  are  all  connected,  either  directly 
or  indirectly,  with  the  theca' of  the  optic  nerve. 

6.  The  Obliquus  Oculi  Inferior  is  at  the  bottom  of  the 
orbit.  It  arises,  by  a small  tendinous  beginning,  from  the 
upper  maxilla  at  the  side  of  the  os  unguis,  and  increasing 
in  size,  it  goes  below  the  rectus  inferior  outwards  and  back- 

* Bulbum  in  priora  et  angulum  internum  versus  inovet;  pupillam  deor- 
sum  ad  genam  dirigit;  juvante  musculo  obliquuo  inferiori  bulbum  nasum 
versus  trahit;  animi  fastum  exprimit;  ira  valde  commoveri  videtur, 


392 


NERVOUS  sySTEM. 


wards,  and  gets  between  the  eyeball  and  the  rectus  exter- 
nus.  It  is  then  inserted  into  the  outer  face  of  the  sclerotica, 
about  half  way  between  the  optic  nerve  and  the  cornea. 

It  causes  the  eye  to  revolve  on  its  axis,  and  turns  the  ball 
towards  the  nose.  Its  action,  however,  is  much  modified  by 
that  of  the  other  muscles. 

Of  the  Lachrymal  Apparatus. 

The  apparatus  for  the  tears  ( Organa  Lachrymalia,  vise 
Lachrymales)  consists  in  the  Lachrymal  Gland,  the  La- 
chrymal Ductsj  the  Lachrymal  Sac,  and  a few  other  parts. 

The  Lachrymal  Gland  [Glandula  Lachrymalis)  is  situ- 
ated in  the  orbit,  immediately  below  and  within  the  external 
angular  process  of  the  os  frontis.  It  secretes  the  moisture 
that  lubricates  the  eyelids  and  eyeball,  and  which,  when 
it  becomes  abundant,  is  called  the  Tears.  It  is  a flattened 
oblong  or  oval,  convex  above  and  concave  below,  of  ten 
lines  in  length,  six  in  width,,  and  about  two  lines  at  its 
thickest  part,  for  its  edges  are  somewhat  beveled.  It  may 
be  considered  as  divided  into  two  parts  or  lobes,  of  which 
the  superior  is  the  larger  and  occupies  the  depression  attri- 
buted to  it  in  the  frontal  bone,  while  the  inferior,  being  the 
smaller,  is  placed  at  the  anterior  margin  of  the  depression. 
It  is  lined  below  by  the  conjunctiva,  and  is  protected  in  front 
by  the  margin  of  the  orbit  which  it  touches. 

This  gland  resembles  much  the  salivary  in  its  light  pink 
colour,  and  in  its  consisting  in  a congeries  of  lobules  united 
by  cellular  substance.  Unless  we  are  to  consider  the  latter 
as  such,  it  has  no  regular  capsule.  From  the  lachrymal 
gland,  there  proceed  six  or  seven  excretory  canals,  extreme- 
ly fine,  and  found  with  so  much  difficulty  that  many  distin- 
guished anatomists  have  sought  for  them  in  vain.*  The 

* These  are  Morgagni,  Haller,  Zlnn,  and  Duverney.  Meckel,  Soemmer- 
ing, and  many  others,  speak  with  all  confidence  concerning  them.  Bichat 
admits  that  he  only  acknowledges  their  existence  inductively.  Dr.  Monro, 

Edinburgh,  claims  to  have  discovered  them  by  plunging  the  eye  into  a 


EYE. 


393 


orifices  of  these  ducts  have  been  laid  down,  by  Soemmering, 
as  equi-distant,  forming,  in  the  conjunctiva,  a row  half  an 
inch  long,  and  parallel  with  the  superior  margin  of  the  tar- 
sus cartilage,  beginning  a quarter  of  an  inch  above  its  ex- 
ternal end,  and  going  inwards.  I have,  on  several  occasions, 
supposed  myself  to  have  passed  bristles  into  these  orifices, 
but,  after  the  doubts  expressed  by  Bichat,  am  disposed  to 
hesitate  in  the  opinion  of  the  real  direction  which  the  bris- 
tles took.  One  fact  is  certain,  that,  by  squeezing  the  gland, 
small  drops,  like  tears,  will  appear  on  the  nearest  surface  of 
the  conjunctiva,  but  not  in  the  regular  order  laid  down  by 
anatomists  for  the  lachrymal  orifices. 

The  Lachrymal  Ducts  {Canaliculi  Lachrymales)  are  si- 
tuated immediately  beneath  the  skin,  at  the  internal  com- 
missure of  the  eyelids,  in  their  posterior  margin,  and  be- 
hind the  orbicularis  muscle.  There  is  one  for  each  eyelid. 
They  are  about  an  inch  long,  though  the  lower  one  is  rather 
longer  than  the  upper. 

The  lachrymal  ducts  commence  at  a small  elevation  of 
the  margin  of  each  eyelid,  bordering  immediately  upon  the 
internal  end  of  the  tarsus  cartilage,  but  perfectly  distinct 
from  it.  This  elevation  is  conical,  and  points  towards  the 
ball  of  the  eye;  in  its  centre  is  a very  small  foramen,  called 
the  Punctum  Lachrymale,  which  is  the  beginning  of  the  la- 
chrymal duct.  The  punctum  is  about  a line  in  length,  and 
enlarging  in  its  course,  it  runs  at  right  angles  to  the  duct 
into  which  it  empties,  of  which  it  may  be  called  tbe  Orbital 
Orifice;  the  upper  one  will,  therefore,  ascend,  and  the  lower 
one  descend. 

The  lachrymal  ducts  are  much  larger  than  the  puncta,  be- 
ing, in  their  whole  course,  about  one  line  in  diameter.  At 
their  orbital  extremities,  they  go  rather  beyond  the  puncta, 
so  as  to  form  a small  cul-de-sac.  These  canals  converge, 
and  having  got  to  the  internal  angle  of  the  eyelid,  they 
are  there  placed  behind  the  internal  palpebral  ligament. 

coloured  fluid  which  was  absorbed  by  them.  Dr.  W.  Hunter  seems  to  have 
a prior  claim  to  Dr.  Monro.  See  Med.  Comment,  p.  54. 

VoL.  II.— 50 


J94 


NERVOUS  SYSTEM. 


They  then  discharge,  by  distinct  orifices,  but  very  near  each 
other,  into  the  lachrymal  sac  at  its  external  anterior  part, 
where  they  form  a small  round  projection  in  the  interior  of 
its  cavity,  and  are  overlapped,  sometimes,  by  a small  dupli- 
cature  of  its  lining  membrane.  When  the  eyelids  are  closed, 
the  lachrymal  ducts  are  horizontal  and  nearly  parallel,  but 
when  the  eye  is  open  the  upper  duct  is  elevated,  and  there- 
by becomes  oblique;  it  is  hence  more  proper  for  the  intro- 
duction of  instruments  into  the  lachrymal  sac. 

The  Lachrymal  Caruncle  {Caruncula  Lachrymalis)  is 
placed  precisely  in  the  angle  formed  by  the  internal  junction 
of  the  eyelids.  It  is  a red  coloured  tubercle,  differing  in  size 
in  different  individuals,  but  commonly  as  large  as  a grain  of 
wheat.  It  is  conical,  and  obtains  its  redness  from  the  con- 
junctiva, being  reflected  over  it:  when  accurately  examined, 
it  will  be  found  to  consist  in  a group  of  sebaceous  glands,  of 
which,  according  to  some  anatomists,  there  are  seven,  ranged 
two  in  a row,  and  one  on  the  top  of  the  others.  The  surface 
of  this  body  is  beset  with  very  fine  hairs,  and  the  orifices  in 
it  are  distinguishable  with  a glass. 

The  Semilunar  Valve,  or  Fold,  {Plica  Semilunaris,)  is 
situated  immediately  at  the  ocular  margin  of  the  caruncle. 
It  has  the  form  of  a triangle,  the  point  of  which  runs  into  the 
caruncle,  and  the  base,  which  is  somewhat  crescentic,  is  di- 
rected towards  the  eye.  It  is  a duplicature  of  the  conjuncti- 
va, which  becomes  very  manifest  from  behind,  and,  in  some 
cases,  has  its  base  furnished  with  a very  small  strip  of  car- 
tilage. * I have  seen  several  cases  of  the  kind  very  well 
marked:  they  occur  more  frequently  in  the  African,  accord- 
ing to  my  personal  experience.  Between  the  base  and  the 
caruncle  it  is  formed  into  a number  of  loose  wrinkles,  which 
disappear  when  the  eye  is  very  much  abducted. 

This  body,  in  the  human  subject,  is  evidently  intended 
to  permit  to  the  eye  a great  freedom  of  abduction.  Its 
analogy,  however,  with  the  third  eyelid  of  animals  is  very 
striking,  and  the  difference  is  rather  in  the  full  develop- 


* Meckel. 


EVE. 


395 


inent  of  the  latter,  than  in  the  organization.  It  is  very 
properly  remarked  by  J.  F.  Meckel,  that  in  descending  the 
scale  of  animals,  the  third  eyelid  is  alw'ays  in  an  inverse 
ratio  to  the  other  two,  till  it  ends  by  being  a complete  sub- 
stitute for  them. 

Surrounding  the  caruncle  may  be  observed  a depression 
on  the  adjoining  part  of  the  plica  semilunaris.  Into  this 
depression  the  puncta  lachrymalia  are  directed  and  there 
play  up  and  down;  the  tears  accumulate  in  it,  from  which 
cause  the  depression  is  called  Lacus  Lachrymalis. 

The  Lachrymal  Sac  {Saccus  Lachrymalis)  is  placed  at 
the  internal  canthus  of  the  orbit;  in  the  depression  of  the 
os  unguis,  and  of  the  nasal  process  of  the  upper  maxillary 
bone.  It  is  an  oblong  cylindroid  cavity;  and  extends  from 
the  transverse  facial  suture  to  the  anterior  extremity  of  the 
inferior  meatus  of  the  nose,  being  concealed  there  by  the 
anterior  part  of  the  inferior  turbinated  bone.  It  is  crossed 
at  its  front  part  by  the  tendon  of  the  orbicularis,  which 
with  a few  fibres  of  this  muscle  adheres  to  it. 

The  course  of  the  lachrymal  sac  is,  at  first,  slightly  for- 
wards in  its  descent  to  the  nose,  but  when  it  reaches  the 
lower  part  of  the  orbit,  it  is  afterwards  sliglitly  backwards, 
so  that  in  its  course  it  may  be  considered  as  forming  an  ob- 
tuse angle  forwards.  It  also  decreases  somewhat  in  size 
from  above  downwards,  and  at  its  lower  orifice  is  flattened 
from  side  to  side. 

The  lachrymal  sac  consists  in  two  membranes,  an  exte- 
rior fibrous  one  continuous  with  the  periosteum  of  the  con- 
tiguous bones;  and  an  interior  one  which  is  thick,  villous, 
of  a red  colour,  and  abounding  in  mucous  follicles.  The 
interior  is  continuous  above  with  the  lachrymal  ducts,  and 
below  with  the  Schneiderian  membrane.  On  a line  with 
the  floor  of  the  orbit,  this  internal  membrane  is  thrown  into 
a circular  duplicature,  considered  by  some  anatomists  as 
forming  the  proper  boundary  of  the  lachrymal  sac;  all  be- 
low this  is  called  by  them  nasal  canal.  The  distinction  is 
rather  arbitrary,  and  in  some  degree  hurtful  to  clearness  of 


NERVOUS  SYSTEM. 


3yu 

description;  a much  better  plan  is  to  call  the  part  above  the 
valve,  the  orbital  portion  of  the  sac;  and  the  part  below  the 
valve,  its  nasal  portion.  Sometimes  there  is  a second  valve 
about  three  lines  below  the  first,  and  also  another  at  the 
nasal  orifice,  formed  by  a duplication  of  the  Schneiderian 
membrane. 

The  Tensor  Tarsi  is  a small  muscle  on  the  orbital  face  of 
the  lachrymal  sac,  and  of  which  I gave  a detailed  account 
some  few  years  ago.'^  It  arises  from  the  posterior  superi- 
or part  of  the  os  unguis,  just  in  advance  of  the  vertical  su- 
ture between  the  os  planum  and  the  os  unguis.  Having 
advanced  three  lines,  it  bifurcates;  one  bifurcation  is  insert- 
ed along  the  upper  lachrymal  duct,  and  terminates  at  its 
punctum,  or  near  it;  and  the  lower  bifurcation  has  the  same 
relation  to  the  lower  lachrymal  duct.  The  base  of  the  ca- 
runcula  lachrymalis  is  placed  in  the  angle  of  the  bifurca- 
tion. The  superior  and  the  inferior  margins  of  the  muscle 
touch  the  corresponding  fibres  of  the  orbicularis  palpebra- 
rum, where  the  latter  is  connected  with  the  margin  of  the 
internal  canthus  of  the  eye,  but  may  be  readily  distin- 
guished by  their  horizontal  course.  The  nasal  face  of  this 
muscle  adheres  very  closely  to  that  portion  of  the  sac 
which  it  covers,  and  also  to  the  lachrymal  ducts.  The 
lachrymal  sac  rises  about  a line  above  its  superior  margin, 
and  extends  in  the  orbit  four  lipes  below  its  inferior  margin. 
The  orbital  face  of  the  musclt  is  covered  by  a lamina  of 
cellular  membrane,  and  between  this  lamina  and  the  ball  of 
the  eye  are  placed  the  valvula  semilunaris,  and  a considera- 
ble quantity  of  adipose  matter. 

As  the  bifurcated  extremities  of  the  muscle  follow  the 
course  of  the  ducts,  they  are  covered  by  the  tunica  con- 
junctiva. When  this  muscle  is  examined  from  behind,  the 
eyelids  being  in  situ,  it  becomes  olivious  that  it  is  concave 
on  its  orbital  surface,  and  consequently  convex  on  the  nasal; 
that  the  muscle  is  an  oblong  body,  half  an  inch  in  length, 
and  about  three  lines  wide,  bifurcated  at  one  end;  and  that 
it  arises  much  deeper  from  the  orbit  than  any  acknowledged 

* Vhilaclelphia  Journal  of  Med.  and  Phys.  Sciences,  1824. 


EYE. 


397 


origin  of  the  orbicularis.  The  superior  fork,  however,  has 
a few  of  its  fibres  blended  with  the  orbicularis. 

In  regard  to  the  use  of  this  muscle;  its  attachment  to 
the  posterior  face  of  the  sac  is  such,  that  it  draws  the  or- 
bital parietes  of  the  sac  away  from  the  nasal,  and  dilates  the' 
sac,  owing  to  the  nasal  face  of  the  latter  being  fixed  to  the 
bones.  As  this  muscle- has  a cylindrical  concavity  on  its 
orbital  side,  it  is  evident  that  when  it  contracts  the  fibres 
become  straight,  or  nearly  so,  like  the  fibres  of  the  dia- 
phragm, and  the  cavity  of  the  sac  is  enlarged  after  the  same 
manner  as  the  cavity  of  the  thorax.  A tendency  to  a va- 
cuum being  thus  produced  by  it,  the  valves  or  folds  of  the 
internal  membrane  of  the  sac  permit  the  vacuum  to  be 
filled  more  readily  through  the  puncta  than  from  the  nose; 
and  the  puncta  being  continually  bathed  in  the  tears  of  the 
lacus  lachrymalis,  both  in  the  waking  and  in  the  sleeping 
state,  the  tears  are  constantly  propelled  through  them  by 
atmospheric  pressure.  The  evacuation  of  the  sac  is  no 
doubt  accomplished  by  its  own  elasticity,  and  by  the  con- 
traction of  the  orbicularis;  probably  in  a chief  degree  by 
the  latter,  because  in  persons  who  have  epiphora,  or  a ten- 
dehcy  to  obstruction  in  the  nasal  duct,  the  accumulation  of 
tears  and  matter  principally  takes  place  at  night,  when  the 
action  of  the  orbicularis  is  suspended  by  sleep.  For  these 
reasons  we  should  argue,  that  this  little  muscle  is  active 
at  all  times,  both  niglit  and  day.  To  Dr.  Physick  I am  in- 
debted for  suggesting  another  use  for  it;  to  wit,  that  of 
keeping  the  lids  in  contact  with  the  ball  of  the  eye  Some 
persons  possess  unusual  voluntary  power  of  this  muscle,  of 
which  I have  seen  two  examples;  one  in  a lady;  another  in 
a gentleman,  a student  of  medicine.  In  each  instance  the 
individual  could  shorten  so  much  the  internal  angle  of  the 
eyelids,  as  to  conceal  it,  along  with  the  puncta,  in  the  in- 
ternal canthus  of  the  orbit.* 

* Having'  laboured,  first  of  all,  to  convince  the  profession  of  the  exist- 
ence of  this  muscle,  the  next  step,  as  is  usual  on  such  occasions,  was  to 
vindicate  my  own  pretensions  to  its  discovery,  and  to  attempt  to  remove 
such  objections  as  requh-ed  attention.  For  the  arguments  on  this  subject 
I refer  to  the  Philadelphia  Journal  of  Medical  and  Physical  Sciences,  of 


NKRVOUS  SVSTEM- 


■jys 

Of  the  Nerves  of  the  Orbit. 

In  addition  to  the  optic  nerve,  there  are  several  belong- 
ing to  the  eye  and  to  its  auxiliary  parts;  they  are  derived 
from  the  Motor  Oculi  or  third  pair;  from  the  Trochlearis, 
or  fourth  pair;  from  the  first  branch  of  the  Trigeminus,  or 
fifth  pair;  and  from  the  Motor  Oculi  Externus  or  sixth  pair. 
For  an  account  of  which,  see  Nerves. 

Of  the  Arteries  of  the  Orbit. 

The  Eyeball  and  its  auxiliary  parts  are  principally  sup- 
plied by  the  Ophthalmic  Artery,  which  as  was  mentioned 
in  the  account  of  the  Brain  is  a considerable  branch  given 
off  by  the  Internal  Carotid  at  the  fore  part  of  the  Sella  Tur- 
cica. This  branch  gets  into  the  orbit  on  the  outer  side  of 
the  optic  nerve  through  the  optic  foramen,  and,  after  a 
short  course,  crosses  obliquely  above  the  optic  nerve,  so  as 
to  get  to  the  internal  side  of  the  orbit.  It  sends  oflf  a great 
many  small  trunks,  which  are  very  inconstant  both  in  their 
size  and  origin;  they  are  as  follow: 

1.  Arteria  Lachrymalis  arises,  commonly,  soon  after  the 
ophthalmic  has  got  into  the  orbit:  it  goes  forwards  between 
the  rectus  superior  and  the  rectus  externus  muscle,  to  which 
it  distributes  arterioles;  it  then  reaches  the  lachrymal  gland, 
and  having  left  branches  with  it,  what  remains  issues  out  at 
the  external  angle  of  the  eye,  so  as  to  supply  the  contigu- 
ous part  of  the  upper  eyelid. 

2.  Arterias  Ciliares.  According  to  Soemmering, ‘before 
the  origin  of  the  lachrymal  artery,  the  ophthalmic  detaches 
from  one  to  three  ciliary,  which  penetrate  into  the  ball  of 

Nov.  1824,  edited  by  Professor  Chapman.  My  claims  have  been  unequivo- 
cally admitted  by  Messrs.  Breschet  and  Jourdan,  of  Paris,  anatomists  of 
unusual  distinction,  in  the  translation  which  they  have  made  of  J.  F.  Mec- 
kel’s Manual  of  Anatomy,  vol.  iii.  p.  219;  by  Gery,  in  the  Melanges  de 
Chirurgie  etrangere,  Geneva,  1824,  p.  415;  and  by  Professor  Giuseppe 
Trasmondi,  in  the  Arcadica  Journal  of  Rome,  vol.  xix.  p.  1.  1823. 


EYE. 


399 


the  eye  near  the  optic  nerve.  Other  arteries  of  the  same 
class  arise  subsequently  from  the  ophthalmic,  and  occasion- 
ally some  of  them  from  the  lachrymal  itself.  They  go  to 
the  choroid  coat  of  the  eyeball  and  to  the  iris. 

3.  The  Arteria  Centralis  Retinae  arises  from  araons  the 
cluster  of  ciliary  arteries,  and  like  them  has  no  invariable 
root.  It  penetrates  the  optic  nerve  about  the  middle  of  its 
orbitar  section,  and  going  in  its  centre  gets  into  the  eye 
through  the  cribriform  part  of  the  sclerotica.  It  is  then 
distributed  by  ramuscles  to  the  retina,  to  the  tunica  hya- 
loidea,  and  to  the  capsule  of  the  lens. 

4.  The  Arteria  Ethmoidea  Posterior  is  inconstant  in  ex- 
istence, and  comes  at  one  time  from  the  trunk,  at  another 
from  a branch  of  the  ophthalmic.  It  passes  over  the  supe- 
rior oblique  muscle,  and  penetrating  through  the  posterior 
orbitary  foramen,  is  spent  by  arterioles  upon  the  neighbour- 
ing part  of  the  dura  mater,  and  upon  the  posterior  ethmoidal 
cells,  where  it  anastomoses  upon  the  Schneiderian  mem- 
brane, with  branches  from  the  internal  maxillary. 

5.  Arteriae  Musculares;  Of  these  there  are  two;  one  of 
them,  the  inferior,  sends  branches  to  the  rectus  internus,  rec- 
tus inferior,  and  obliquus  inferior  oculi,  also  to  the  lachrymal 
sac,  and  to  the  parts  about  the  bottom  of  the  orbit.  It  occa- 
sionally detaches  some  of  the  ciliary  arteries.  The  superior 
muscular  branch  is  also  called  the  supra  orbitar.  It  supplies 
the  muscles  of  the  superior  part  of  the  orbit,  and  then  issuing 
through  the  supra  orbitary  foramen,  it  is  spent  in  arterioles 
upon  the  os  frontis  and  its  periosteum,  and  upon  the  orbicu- 
laris oculi,  corrugator  supercilii,  and  occipito  frontalis.  It 
anastomoses  there  with  other  branches  of  the  ophthalmic, 
and  with  the  temporal  artery. 

It  is  usual  for  the  anterior  ciliary  arteries,  to  come  from 
the  muscular  branches. 

The  Ophthalmic  Artery,  after  having  detached  all  the 
aforesaid  branches,  is  much  diminished  in  volume,  and  ad- 
vancing along  the  internal  parietes  of  the  orbit,  its  next 
branch  is 


400 


NERVOUS  SYSTEM. 


6.  The  Arteria  Ethmoidea  Anterior,  which  dips  into  the 
anterior  internal  orbitary  foramen,  and  is  divided  into  small 
branches,  some  of  which  are  spent  upon  the  adjacent  por- 
tion of  the  dura  mater,  others  upon  the  frontal  sinus  and 
the  anterior  ethmoidal  cells.  Some  of  these  branches  pene- 
trate from  the  cranium  through  the  cribriform  bone  into 
the  nose,  and  ramifying  upon  the  Schneiderian  membrane, 
anastomose  with  the  internal  maxillary. 

7.  The  Arteriag  Palpebrales  are  two  in  number;  they 
come  sometimes  from  a common  trunk,  and  on  other  occa- 
sions arise  separately.  One  is  the  Superior,  and  the  other 
the  Inferior;  the  latter  arises  first,  and  is  distributed  to  the 
conjunctiva,  the  caruncula  lachrymalis,  lachrymal  sac,  and 
finishes  by  many  small  branches  to  the  lower  eyelid,  that 
anastomose  with  the  infra-orbital  artery,  so  as  to  form  the 
lower  tarsal  arch.  It  also  anastomoses  with  the  lachrymal 
artery  by  its  extreme  branches. 

The  Superior  Palpebral  Artery  also  distributes  branches 
to  the  conjunctiva,  sac,  and  caruncle;  it  then  emerges  above 
the  palpebral  ligament,  around  the  margin  of  the  superior 
eyelid,  and  forms,  along  with  the  lachrymal  and  the  supra 
orbital  artery,  the  superior  tarsal  arch,  which  distributes 
small  branches,  in  great  profusion,  to  the  orbicularis  mus- 
cle, and  to  the  structure  generally  of  the  lid.  It  anastomoses 
externally  with  the  lower  palpebral  artery. 

8.  The  Arteria  Nasalis  is  sometimes  a well  marked  con- 
tinuation of  the  ophthalmic.  It  passes  out  of  the  orbit  at  its 
internal  canthus,  above  the  internal  palpebral  ligament,  and 
anastomoses  at  the  root  of  the  nose  with  the  facial  artery. 
It  is  distributed  to  the  side  of  the  nose,  and  to  the  lower 
part  of  the  forehead.  Its  chief  contribution  to  the  eyelids 
is  at  the  internal  end  of  the  orbicularis,  where  it  anastomoses 
with  the  palpebral  arteries. 

9.  The  Arteria  Frontalis  passes  out  of  the  orbit,  at  the 
upper  part  of  the  internal  canthus.  It  is  quickly  divided 
into  branches,  which  go  to  the  orbicularis  and  corrugator 
muscles,  to  the  occipito-frontalis,  and  to  the  frontal  sinus. 


JilTJa. 


401 


Of  the  Veins  of  the  Orbit. 

The  blood  distributed  to  the  eyeball  and  to  its  auxiliaiy 
parts,  has  two  routes  for  returning  to  the  heart,  one  through 
the  cavernous  sinus  of  the  brain,  and  the  other  by  the  super- 
ficial veins  of  the  face.  As  a general  rule,  all  the  branches 
of  the  ophthalmic  artery  which  reach  the  eyelids,  or  become 
otherwise  superficial,  return  their  blood  by  the  latter  route; 
and  those  whose  distribution  is  to  the  ball  of  the  eye  and  to 
the  parts  deeply  seated  in  the  orbit,  return  their  blood  by 
the  sinus. 

When  the  veins  are  well  injected,  a very  considerable 
number  is  manifested  in  both  eyelids.  They  form  a hand- 
some network,  the  meshes  of  which  are  small  and  numerous, 
and  commence  by  small  roots  at  the  margin  of  the  eyelids. 
The  vessels  of  this  network  becoming  successively  larger 
from  the  centre  to  the  circumference  of  the  orbicularis, 
cover  the  whole  surface  of  the  latter,  and  from  the  thinness 
of  the  skin  are  readily  seen  beneath  it.  The  veins  of  the 
lower  eyelid  are  discharged  into  the  facial  vein,  where  it 
borders  on  the  orbicularis,  and  the  veins  of  the  upper  lid 
being  bordered  along  the  superior  margin  of  the  orbicularis 
by  a horizontal  branch  of  the  temporal  vein,  discharge 
themselves  into  it. 

The  Ophthalmic  Vein  {Simis  Ophthalmicus)  is  the  large 
trunk  within  the  orbit  which  receives  successively  the  re- 
maining blood  of  the  eye,  and  passing  along  the  internal 
parietes  of  the  orbit,  crosses  over  the  optic  nerve,  and  pene- 
trates through  the  optic  foramen  into  the  cavity  of  the  cra- 
nium, where  it  terminates  in  the  cavernous  sinus.  It  may 
be  considered  as  commencing  by  an  anastomosis  with  the 
facial  vein  at  the  internal  canthus;  it  then  receives  the  fol- 
lowing branches: 

1.  The  nasal,  which  arises  from  the  parts  about  the  inter- 
nal canthus  of  the  eye. 

2.  The  anterior  ethmoidal,  which  comes  from  the  nose 
and  frontal  sinus. 

VoL.  II.— 51 


NERVOUS  SYSTEM. 


40ii 

3.  Branches  from  the  recti  and  obliquui  muscles. 

4.  The  lachrymal  vein,  from  the  lachrymal  gland  and 
levator  palpebrse  muscle. 

5.  Posterior  ethmoidal  vein,  from  the  nose. 

G.  The  ciliary  veins,  or  those  of  the  choroid  coat,  which 
are  very  numerous. 

7.  The  central  vein  of  the  retina,  which  is  collected  from 
three  or  four  principal  branches,  and  follows  the  course  of 
the  artery  of  the  same  name,  through  the  cribriform  part  of 
the  sclerotic  coat,  and  through  the  centre  of  the  optic  nerve. 
The  trunks  of  this  vein  anastomose,  at  the  anterior  margin 
of  the  retina,  with  those  of  the  Ciliary  Body. 

There  are,  of  course,  frequent  anastomoses  between  the 
veins  of  the  eyelids  and  the  primitive  branches  of  the  oph- 
thalmic vein. 

SECT.  II. — OP  THE  BALL  OP  THE  EYE. 

The  Eyeball  {Bulbus  Oculi)  is  situated  within  the  ante- 
rior half  of  the  orbit,  from  which  it  is  kept  separated  by  its 
auxiliary  parts,  and  by  a large  quantity  of  adipose  matter 
which  fills  up  their  interstices.  It  it  very  nearly  spheroi- 
dal, but  not  so  much  so  as  to  prevent  its  antero  posterior 
diameter,  which  is  about  an  inch  long,  from  exceeding  in 
measurement  every  other.  Such  is  the  general  opinion  of 
anatomists,  but  from  some  recent  experiments,  made  by 
distending  the  eye  with  mercury,  I have  been  induced  to 
doubt  its  correctness,  and  especially  in  the  African;  for  in 
the  latter  I found  the  transverse  diameter  to  exceed  the  an- 
tero-posterior  by  a line  or  more. 

It  is  formed  by  a series  of  concentric  tunics,  one  invest- 
ing the  other,  and  by  humours  contained  within  those  tu- 
nics. Of  the  former  the  Sclerotica  and  the  Cornea  are  ex- 
ternal, the  Choroidea  and  the  Iris  next,  and  the  Retina  is 
internal;  of  the  latter  the  Vitreous  Humour  is  by  far  the 
most  abundant,  and  constitutes  a principal  part  of  the  eye- 
ball, being  situated  in  its  posterior  part;  the  Crystalline 
Humour  is  in  front  of  the  vitreous;  and  the  Aqueous  is 
placed  between  the  crystalline  and  the  Cornea, 


THE  BALL  OP  THE  EYE. 


403 


Tunics  or  Membranes  of  the  Eyeball. 

The  Sclerotic  Coat  ( Tunica  Sclerotica,  Albuginea) 
forms  about  five-sixths  of  the  exterior  investment  of  the 
eyeball,  the  remaining  sixth  of  which  is  obtained  from  the 
cornea.  At  its  posterior  part  it  is  joined  by  the  optic  nervej 
this  junction  does  not  occur  precisely  at  its  axis  or  centre, 
but  at  the  inner  side  of  it.  When  the  optic  nerve  is  de- 
tached at  this  junction,  a small  round  hole  is  perceptible  in 
the  sclerotica,  or  rather  it  is  more  frequently  perceived  as 
a thin  cribriform  lamella,  through  the  holes  of  which  the 
pulpy  part  of  the  optic  nerve  passes,  so  as  to  get  within 
the  eye.  This  cribriform  lamella,  or  the  appearance  of  it, 
is  no  doubt  produced  artificially  by  the  nerve  being  com- 
monly cut  through  very  near  the  eye,  and,  as  Mr.  Jacobs, 
of  Dublin,  very  properly  suggests,  should  be  considered  as 
the  most  anterior  termination,  or  the  point  of  the  optic 
nerve,  instead  of  as  a portion  of  the  sclerotica.  The  neu- 
rileme  of  the  optic  nerve  is  so  arranged,  that  small  round 
longitudinal  canals  are  left,  which  contain  the  nervous  mat- 
ter; from  this  cause  it  happens  that  a thin  section  of  the 
optic  nerve  in  any  part  of  its  course  in  the  orbit,  will,  if 
held  up  to  the  light,  manifest  the  same  cribriform  arrange- 
ment with  the  part  alluded  to.  This  part  of  the  structure 
of  the  optic  nerve  will  be  readily  understood  by  the  Ame- 
rican student,  in  comparing  it  with  the  pith  of  the  Indian 
corn-stock,  which,  being  traversed  longitudinally,  by  many 
fibres,  upon  the  drawing  of  them  out,  an  equal  number  of 
longitudinal  canals  is  left  in  their  places. 

At  its  fore  part,  the  edge  of  the  sclerotica  for  its  junc- 
tion with  the  cornea,  is  bevelled  all  around;  and  though 
nearly  circular,  is  not  completely  so,  from  its  horizontal 
diameter  being  somewhat  greater  than  any  other.  There 
are  several  orifices  of  inconsiderable  size  scattered  over  the 
sclerotica,  some  of  which  are  oblique  and  others  direct;  they 
transmit  the  blood  vessels  and  nerves.  The  sclerotica  is 
nearly  a line  in  thickness  at  its  back  part,  from  which  it 


101 


XERVOUS  SYSTEM. 


gradually  becomes  reduced  to  half  that  thickness  in  front, 
where  it  is  strengthened  by  the  tendinous  insertions  of  the 
recti  muscles.  Its  internal  surface  is  smooth  and  somewhat 
shining,  being  loosely  attached  to  the  cellular  substance  in- 
tervening between  it  and  the  choroid  coat;  but  the  exter- 
nal surface  is  rough  and  more  obviously  fibrous,  being  at- 
tached somewhat  strongly  to  all  the  adjoining  parts. 

This  membrane  is  of  a white  colour,  and  consists  of  a 
single  layer,  whose  structure  is  essentially  fibrous.  The 
fibres  are  very  closely  compacted,  and  compose  an  inter- 
texture which  cannot  be  unravelled.  It  is  so  closely  united 
to  the  dura  mater  covering  of  the  optic  nerve,  that  many 
anatomists,  notwithstanding  its  greater  thickness,  are  dis- 
posed to  speak  of  it  as  a continuation  of  the  same.  Its 
strength  and  its  want  of  elasticity  suit  it  remarkably  to  main- 
tain the  form  of  the  eye,  and  to  resist  injuries.  Out  of  the 
many  blood  vessels  that  penetrate  it,  but  few  ramify  in  its 
structure,  and  the  existence  of  nerves  in  it  is  by  no  means 
very  evident. 

The  tunica  arachnoidea  follows  the  course  of  the  optic 
nerve,  within  its  coat  of  dura  mater,  and  forms,  just  around 
the  cribriform  plate  or  foramen  of  the  sclerotica,  a circular 
pad;  it  is  then  reflected  on  the  internal  face  of  the  sclerotica, 
as  far  as  its  anterior  opening.  It  is  this  which  causes  the 
internal  face  of  the  sclerotica  to  be  smooth  and  shining,  and 
thereby  to  correspond  with  that  of  the  dura  mater.*  This 
circumstance  is  more  readily  proved  in  a very  young  eye, 
than  in  the  adult  one. 

The  Cornea,  as  mentioned,  fills  up  the  aperture  at  the 
fore  part  of  the  sclerotica,  and,  of  course,  has  the  same  dia- 
meters, measuring  thereby  more  transversely  than  in  any 
other  direction.  It  is  a segment  of  a smaller  sphere  than 
the  sclerotica,  and  is  consequently  more  convex  than  it.  Its 
thickness  is  uniform,  and  commonly  exceeds  that  of  the 
sclerotica  at  the  fore  part  of  the  latter. 

* J.  F.  Meckel.  Zinn  supposed  this  surface  to  be  derived  from  the  pia 
mater. 


THE  BALL  OP  THE  EYE. 


405 


Its  circumference  adheres  very  closely  to  the  sclerotica, 
and  presents  a bevelled  or  oblique  edge,  which  is  inserted 
into  the  corresponding  bevel  of  the  sclerotica,  so  that  the 
latter  includes  the  former.  The  closeness  of  this  junction 
induced  the  older  anatomists  to  consider  these  membranes 
as  one  and  the  same,  notwithstanding  their  obvious  diffe- 
rence of  structure  and  of  properties.  Their  adhesion  yields 
to  protracted  maceration.  The  cornea  is  covered  in  front 
by  a continuation  of  the  tunica  conjunctiva,  which  unites 
the  eyeball  to  the  eyelids.  This  may  be  proved  by  dissec- 
tion, by  maceration,  and  by  its  sloughing  off  entirely  along 
with  the  epidermis  of  animals  that  are  subject  to  this  pro- 
cess, as  the  locust,  snakes  and  others.  On  its  posterior  face, 
it  is  covered  by  the  membrane  of  the  aqueous  humour,  which 
may  be  rendered  evident  by  steeping  it  in  spirits  of  wine, 
whereby  the  latter  membrane  is  made  more  hard,  and  may 
be  torn  off. 

The  cornea,  in  a natural  state,  is  perfectly  transparent, 
and  readily  transmits  the  rays  of  light.  It  consists  of  an 
indefinite  number  of  laminae,  which  are  placed  one  against 
the  other  like  the  leaves  of  a book,  and  are  united  by  a de- 
licate transparent  cellular  substance  which  permits  the  la- 
minae to  slide  upon  each  other.  These  laminae  are  kept 
moist  and  pellucid  by  an  interstitial  secretion  of  a fluid 
equally  pellucid  with  themselves,  the  abundance  of  which 
in  health  gives  to  the  eye  its  brilliancy,  and  the  deficiency 
of  it  in  illness  and  in  death  causes  the  eye  to  look  dim  and 
somewhat  opaque.  Its  evaporation,  which  no  doubt  is  con- 
tinually occurring,  is  as  constantly  supplied  by  a fresh  and 
abundant  secretion.  The  motion  of  the  eyelids  sweeps  the 
residuum,  after  the  evaporation  of  its  watery  particles,  from 
the  surface  of  the  cornea;  without  this  process,  the  residuum 
appears  as  a thin  layer  or  film  of  albuminous  matter  spread 
over  the  cornea,  when  the  eye  is  kept  open  without  wink- 
ing for  a considerable  time. 

The  cornea  has  not  the  fibrous  structure  of  the  sclerotica, 
yet  the  application  of  mechanical  force  to  the  eyeball  shows 
that  it  is  stronger.  Neither  has  it  vessels  conveying  red 


406 


NERVOUS  SYSTEM. 


blood  naturally,  yet,  in  a state  of  inflammation,  its  capilla- 
ries dilate  so  as  to  admit  red  blood,  and  deposite  coagu- 
lating lymph  between  its  layers.  It  is  common  for  anato- 
mists to  attribute  a want  of  sensibility  to  it  in  a natural 
state;  as  a general  rule,  this  is  fallacious:  for  many  persons, 
where  the  eyes  are  not  inflamed,  suffer  extremely  from  its 
being  cut  in  cataract,  and  sometimes  faint  from  the  pain, 
while  others  are  truly  unconscious  of  the  incisions  made 
through  it.  Of  this  opinion,  I have  a full  assurance  from 
repeated  observations  on  the  practice  of  Dr.  Physick,  as 
well  as  in  instances  in  my  own  hands. 

The  Choroid  Coat  ( Tunica  Choroidea,  Vasculosa)  is 
placed  immediately  within  the  circumference  of  the  sclero- 
tica, and  is  of  equal  extent.  At  its  posterior  part  it  fur- 
nishes, for  the  passage  of  the  optic  nerve,  a singular  annu- 
lar opening,  the  margin  of  which  is  somewhat  thickened 
and  perfectly  distinct  from  the  pia  mater  investment  of  the 
nerve,  from  which  some  anatomists  have  desired  to  trace 
this  coat.  The  anterior  opening  of  the  choroid  is  bounded 
by  the  ciliary  ligament  and  by  the  iris.  On  its  outer  side 
may  be  seen  an  abundance  of  that  loose  flocculent  cellular 
substance  which  joins  it  to  the  sclerotica.  Internally,  it  is 
spread  over  the  retina,  but  does  not  adhere  to  it. 

The  choroid  coat  is  closely  fastened,  at  its  anterior  mar- 
gin, to  the  corresponding  part  of  the  sclerotica,  by  a ring 
which  surrounds  it,  of  a short  compact  cellular  tissue.  This 
ring,  called  the  Ciliary  Ligament,  {Ligamentum  Ciliare, 
Orhiculus  Ciliaris,)  is  from  a line  to  two  lines  in  breadth, 
and  may  he  readily  distinguished  by  its  whiteness,  con- 
trasted with  the  dark  colour  of  the  choroid.  It  is  intimately 
united  to  the  latter,  and  seems  to  form  a part  of  its  struc- 
ture, whereby  it  is  caused  to  detach  itself  entirely  from  the 
sclerotica  and  to  adhere,  by  preference,  to  the  choroid  when 
these  two  membranes  are  separated.*  The  iris  is  set  in  the 
front  margin  of  the  ciliary  ligament,  so  that  the  sclerotica 

* Fontana  asserted  that  a circular  canal  was  to  be  found  in  this  ligament ; 
many  examiners  have  failed  in  finding  it,  and  its  existence  is  denied. 


THE  BALL  OP  THE  EYE. 


407 


and  the  cornea  may  be  peeled  from  the  choroidea  and  iris, 
without  impairing  the  continuity  of  the  two  latter.  Just 
beyond  the  junction  of  the  two  last,  the  ligament  presents 
a small  ridge  or  elevation  all  around,  which  is  fitted  into  a 
corresponding  fossa  at  the  circumference  of  the  internal  face 
of  the  cornea. 

The  internal  face  of  the  choroid  coat,  as  well  as  its  ante- 
rior margin,  undergo  a very  remarkable  change  from  the 
general  plan  of  this  tunic,  by  forming  what  is  called  the 
Ciliary  Body  {Corpus  Ciliare,  Corona  Ciliaris.)  In  or- 
der to  see  this  in  the  most  favourable  manner,  the  eye  should 
be  laid  on  the  cornea,  and  its  posterior  half  cut  away.  It 
will  then  be  evident,  that  just  behind  the  iris,  and  within 
the  circumference  of  the  ciliary  ligament,  the  internal  face 
of  the  choroid  coat  forms  a considerable  number  of  radiated 
folds  or  little  ridges,  which  converge  from  behind  forwards 
and  inwards.  These  folds  commence  by  striae,  almost  im- 
perceptible to  the  naked  eye,  which  are  in  contact  with  the 
fore  part  of  the  vitreous  humour  and  with  the  canal  of  Pe- 
tit, and  thereby  not  only  impress  the  neighbouring  portion 
of  the  tunica  hyaloidea  with  their  shape,  but  even  leave 
upon  it  the  black  pigment  with  which  they  themselves  are 
covered.  These  folds,  when  they  get  near  the  circumference 
of  the  iris,  coalesce  one  with  another,  and  terminate  in  a 
considerable  number  (from  fifty  to  sixty,  according  to  Soem- 
mering) of  processes,  {Processus  Ciliares,)  the  central  ex- 
tremities of  which  are  loose,  and  float  in  the  aqueous  hu- 
mour. Some  of  these  processes  are  longer  than  others.  As 
a whole,  the  ciliary  processes  constitute  a ring  of  radiating 
filaments,  which  are  a line  or  more  in  length,  placed  along 
side  of,  and  in  contact  with,  one  another;  the  external  peri- 
phery of  the  ring  adheres  to  the  ciliary  ligament,  and  through 
it  to  the  greater  circumference  of  the  iris,  so  that  the  ring 
appears,  but  fallaciously,  to  be  continuous  with  the  iris.  In 
certain  animals,  as  the  sheep,  the  radiated  appearance  of  the 
iris,  on  its  posterior  face,  favours  this  notion  still  more. 
The  internal  periphery  of  the  ring  presents  the  central 
ends  of  the  filaments  detached  from  one  another,  and  of  a 


40S 


NERVOUS  SYSTEM. 


downy  appearance;  with  the  handle  of  a knife  they  may 
be  readily  pushed  backwards  and  forwards.  Generally 
speaking,  the  ciliary  processes  are  so  much  concealed  by 
the  iris,  that  they  cannot  be  seen  in  the  living  body  through 
the  cornea;  in  cases,  however,  of  extreme  dilatation  of  the 
pupil  by  narcotic’ applications,  their  central  extremities  are 
brought  into  view. 

The  choroid  coat  always  appears,  when  uninjected,  of  a 
very  dark  brown  or  black  colour,  arising  from  a black  paint 
{Pigmentum  Nigrum)  being  very  thickly  spread  over  the 
whole  of  that  surface  of  it  which  is  adjacent  to  the  retina, 
and  being  also  diffused  through  its  thickness.  This  paint 
is  more  abundant  near  the  iris  than  posteriorly,  being  laid 
on  there  in  flakes,  in  the  intervals  between  the  ciliary  striae, 
and  tinging  also  the  ciliary  processes.  It  may  be  removed 
in  a considerable  degree,  indeed  almost  entirely,  by  mace- 
ration, or  by  careful  washing  with  a camel’s  hair  pencil.  It 
is  supposed  to  be  an  exhalation  from  the  vessels.  Its  par- 
ticular colour  is  of  a most  durable  kind.  According  to  the 
observations  of  Bichat,  the  long  continued  action  of  light 
upon  it,  when  transferred  from  the  choroid  to  a piece  of 
paper,  does  not  affect  it;  neither  is  it  changed  by  being  sub- 
mitted to  very  strong  chemical  agents,  as  sulphuric,  muri- 
atic, or  nitric  acid,  alcohol,  or  caustic  potash.  This  degree 
of  indestructibility  of  colour  is  an  invaluable  property,  and 
almost  singular;  for  it  is  well  known  to  the  keepers  of  me- 
dicinal articles,  that  the  colours  of  all  of  them  yield  to  the 
continued  influence  of  light,  and  that  they  also  become 
weaker  by  the  same  cause. 

In  regard  to  structure,  the  choroid  coat  is  thin,  soft,  and 
easily  lacerated:  wlien  cleared  of  its  pigment  by  maceration, 
it  is  semitransparent,  and  is  then  seen  evidently  to  consist  of 
but  one  lamina;  unless  we  may  be  disposed  to  consider  as  a 
second  one  the  pigment  naturally  on  its  internal  face.  It 
has  no  appearance  of  fibres  in  its  composition,  but  when  in- 
jected seems  to  consist  almost  wholly  of  arteries  and  of 
veins. 


THE  BALL  OF  THE  EYE. 


409 


The  arteries  are  branches  of  the  ophthalmic,  and  are  called 
ciliary.  There  are  two  Long  Ciliary  Arteries,  which  pene- 
trate the  sclerotic  coat  not  far  from  the  optic  nerve,  and 
pass,  one  of  them  on  the  external  and  superior  part  of  the 
choroides,  and  the  other  on  its  inferior  and  nasal  side,  to  the 
front  of  the  eye.  In  this  course,  they  do  not  send  off  any 
branches  of  consequence  till  they  reach  the  iris,  on  which 
they  are  distributed.  The  Short  Ciliary  Arteries  are  much 
more  numerous  than  the  others,  and  also  smaller;  their  num- 
ber sometimes  amounts  to  twenty;  the  most  of  them  pene- 
trate the  sclerotica  from  behind,  near  the  optic  nerve  also.* 
They  quickly  divide  into  a great  number  of  branches,  which 
depart  at  very  acute  angles  and  have  frequent  anastomoses 
with  one  another.  These  branches  run  forwards  nearly  pa- 
rallel, and,  at  the  fore  part  of  the  choroides,  form  a very 
intricate  intertexture,  which  is  continued  upon  the  ciliary 
processes,  and  communicates  with  the  vessels  of  the  iris.t 

The  Veins  of  the  Choroid  Coat  are  also  extremely  abun- 
dant. They  run  from  before  backwards,  and  the  branches 
which  concur  to  form  them,  being  adjacent  with  and  parallel 
to  each  other  for  the  most  part,  form  large  curves,  the  con- 
vexity of  which  is  forwards;  they  moreover  anastomose 
freely,  and  thereby  produce  a vascular  sort  of  net  work, 
filling  up  the  concavity  of  some  of  the  curves.  These  veins, 
called  the  Vasa  Vorticosa,  are  nearer  the  external  surface 
of  the  choroides  than  the  arteries,  and  are  assembled  into 
twelve  or  fourteen  trunks,  which,  engaging  in  the  scleroti- 
ca, near  its  middle,  run  for  some  distance  in  its  substance, 
and  then,  by  their  junction,  are  reduced  to  four  dr  five  in 
number.  The  latter,  disengaging  themselves  from  the  eye, 
join  subsequently  the  ophthalmic  vein. 

In  addition  to  the  veins  mentioned,  the  long  ciliary  arte- 
ries have  their  venae  comites,  which  observe  a course  parallel 
to  and  adjoining  them.  These  veins  do  not  observe  the 
vortical  arrangement  of  the  others,  and  bring  back  the  blood 
of  the  iris;  they  terminate,  however,  in  the  larger  trunks  of 
the  others. 

* Sasmmering,  leones  Oculi  Humani. 

VoL.  II. —52 


f Idem. 


410 


NERVOUS  SYSTEM. 


This  structure  has  been  most  cautiously  explored  by  the 
celebrated  Soemmering,  and  his  observations  have  tended 
very  much  to  determine  the  opinions  of  anatomists  concern- 
ing many  parts  of  the  eye.  A curious  remark  of  his  is,  that 
“the  human  eye  may  be  distinguished  from  that  of  animals 
by  a form  of  this  vascular  net  work,  entirely  peculiar:  for 
example,  in  the  eye  of  the  ape,  its  vascular  tissue  differs  not 
only  from  that  of  the  human  subject,  but  also  from  that  of  the 
dog,  and  still  more  evidently  from  that  of  the  calf.  From 
which  cause,  it  would  be  as  easy  to  distinguish  with  a mi- 
croscope, the  choroides,  well  injected,  of  different  animals, 
even  a piece  of  only  the  forty-eiglith  part  of  an  inch  in  ex- 
tent, as  it  is  easy  to  distinguish  a poplar  stripped  of  its 
leaves  from  an  oak,  a pear  tree,  an  apple,  or  any  other  tree, 
by  the  arrangement  of  its  trunk  and  branches.” 

The  Choroides,  on  its  internal  face,  is  not  smooth,  but 
velvety,  which  becomes  still  more  conspicuous  when  the  eye 
is  finely  injected  and  examined  with  a microscope.  Meckel 
considers  the  appearance  to  depend  upon  its  very  fine  tissue 
of  vessels.  This  surface  is  called  Tapetum.  In  the  bullock, 
at  a particular  part  of  it,  this  surface  presents  a shining, 
silvery  appearance,  and  may  be  torn  off  from  the  external 
surface.  Ruysch  attributed  two  laminae  to  the  membrane 
in  the  human  subject,  the  internal  of  which  was  called  after 
his  name,  but  the  distinction  is  now  generally  abandoned. 

The  Iris  is  a circular  plane  placed  at  the  front  of  the  cho- 
roides, and  having,  in  its  centre,  a round  opening  called  the 
pupil  ) Its  external  circumference  is  attached  to 

the  ciliary  ligament,  and  by  it  to  the  choroid  coat,  and  is 
precisely  at  the  junction  of  the  cornea  with  the  sclerotica. 
Professor  Soemmering  has  bestowed  much  attention  in  as- 
certaining whether  this  membrane  is  perfectly  flat  or  some- 
what convex  in  front,  and,  by  repeated  observations  care- 
fully made,  has  assured  himself  that  it  is  flat.*  My  own 
observations  and  preparations  have  induced  me  to  believe 
that  in  many  cases  it  will  be  found  slightly  convex  in  front. 


leones  Oculi  Humani. 


THE  BALL  OP  THE  EYE. 


411 


&s  Petit  asserted  more  than  a century  ago.  In  a moderate 
state  of  dilatation,  its  nasal  or  internal  border  is  somewhat 
narrower  than  its  external  or  temporal.  With  the  exception 
of  its  external  circumference,  every  part  of  the  iris  is  free 
from  any  attachment;  by  which  arrangement  it  moves  freely 
in  the  aqueous  humour,  so  as  to  contract  or  dilate  its  pupil, 
according  to  the  quantity  of  light  admitted  upon  the  eye. . 

The  iris,  with  the  exception  of  its  central  or  pupillary 
circumference,  where  it  is  thinner  than  elsewhere,  is  much 
thicker  than  the  choroid  coat.  The  posterior  face  of  the  iris, 
sometimes  called  uvea,  is  covered  in  great  abundance  with 
pigmentum  nigrum.  When  this  is  removed  by  maceration, 
which  may  be  readily  done,  the  membrane  becomes  semi- 
transparent. Its  anterior  surface  is  the  seat  of  the  colour, 
which  characterises  every  individual’s  eyes.  There  are  but 
two  of  these  colours,  light  blue  and  orange,  the  predomi- 
nance of  one  or  the  other  of  which,  assisted  by  the  dark 
ground  on  the  back  of  the  iris,  gives  the  cast  of  hue  to  the 
eye.  The  front  surface,  when  examined  on  the  living  eye 
with  the  microscope,  is  seen  to  be  downy  or  flocculent,  and 
is  traversed  by  filaments  forming  an  intertexture,  some  of 
which  are  circular,  others  oblique;  and  others  radiated. 

The  power  which  the  iris  has  of  dilating  the  pupil  when 
there  is  but  little  light,  and  of  contracting  it  when  there  is 
much,  has  induced  many  anatomists  to  think  that  it  is  formed 
of  muscular  radiated  fibres,  which  by  their  contraction  pro- 
duce the  first  motion,  and  of  circular  ones  which  produce  the 
last.  Among  these  anatomists  may  be  mentioned,  Ruysch, 
Morgagni,  Zinn,  Sabatier.  Ruysch  a,sserted  that  the  radiated 
fibres  extended  from,  the  greater  circumference  of  the  iris  to 
the  pupil,  and  were  fixed  there  by  very  delicate  tendons. 
The  late  Doctor  Monro,  of  Edinburgh,  has  described  particu- 
larly the  circular  fibres,  and  a preparation  of  the  bullock’s 
eye  which  belonged  to  him  is  still  exhibited  there,  where 
these  fibres  are  seen  around  the  margin  of  the  pupil.  The 
several  fibres  can  only  be  seen  distinctly,  when  the  pigmen- 
tum nigrum  is  washed  away.  Demours  and  Meckel  deny 
the  existence  of  the  radiated  fibres.  The  late  distinguished 


412 


NKRVOUS  SYSTEM. 


Professor  Wistar  taught  that  the  contraction  of  the  pupil 
was  produced  by  circular  fibres,  and  the  dilatation  of  it  by  . 
its  elasticity.  In  objection  to  this,  Dr.  Physick  remarks,  ' 
that  as  elasticity  is  as  much  a property  of  dead  as  of  living  v 
matter,  in  death  therefore  we  should  always  find  the  pupil  ^ 
dilated  from  the  want  of  active  contraction  in  the  circular 
fibres;  also,  in  cases  of  concussion  of  the  brain,  where  there 
is  a sudden  loss  of  sensibility  and  of  muscular  motion,  the 
pupil  should  be  invariably  dilated,  but  the  fact  is  that  the 
pupil  remains  just  in  the  same  state  that  it  was  at  the  mo- 
ment of  the  accident. 

Notwithstanding  the  extreme  sensibility  and  mobility  of 
the  iris  on  the  admission  of  light,  one  is  occasionally  asto- 
nished to  find  it  not  contracting  whe  i instruments  are  ap- 
plied to  it,  as  I have  had  an  opportunity  of  twice  observing, 
upon  the  removal  of  a considerable  portion  of  it,  in  making 
an  artificial  pupil  for  opacity  of  the  cornea.  In  these  cases 
upon  the  letting  out  of  the  aqueous  humour,  it  became  quite 
as  flaccid  as  we  are  accustomed  to  see  it  in  our  dissections. 
The  same  remark  has  been  made  by  Mr.  Charles  Bell. 

The  Blood  Vessels  of  the  Iris  are  principally  branches  of 
the  Long  Ciliary,  which  have  been  alluded  to.  Each  of  the  ' 
two  Long  Ciliary  Arteries  having  gained  the  greater  cir- 
cumference of  the  iris,  bifurcates;  tbe  bifurcations  run  along 
this  circumference,  meet,  and  join  with  the  corresponding 
ones  of  the  other  arterial  trunk.  From  the  circle  thus 
formed  there  proceed  radiated  branches,  that  run  towards 
the  pupil,  and  form  around  its  margin,  by  their  frequent 
anastomoses,  a fine  vascular  network.  The  radiated  branches 
themselves  give  off  collateral  branches,  which  supply  the  - 
intermediate  spaces  of  the  iris.*  The  Veins  of  the  iris  are 
also  numerous,  but  cannot  be  quite  so  distinctly  seen:  they  ; 
enter  into  the  long  ciliary  veins,  and  also  into  the  vasa 
vorticosa. 

The  Nerves  of  the  Iris  belong,  in  part,  also  to  the  choroid  - 
coat,  and  are  classed  under  the  term  Ciliary  [Nervi  Cili- 
ares.)  They  arise  from  the  ophthalmic  ganglion,  and  from 


* Sammering,  leones  Oculi  Hum. 


THE  BALL  OF  THE  EYE. 


413 


the  trunks  contributing  thereto,  and  are  about  twenty  in 
number.  They  penetrate  the  posterior  part  of  the  sclerotica 
obliquely,  and  then  run  forwards  between  it  and  the  cho- 
roides.  Having  reached  the  posterior  part  of  the  ciliary 
ligament,  they  penetrate  it,  and  distribute  their  filaments  in 
its  substance,  after  the  same  fashion  that  the  trigeminus 
nerve  is  divided  in  its  ganglion.  This  circumstance  has 
given  occasion  to  Soemmering,  to  consider  the  ligament  as 
a true  ganglion,  and  to  call  it  Annulus  Gangliformis.  The 
nerves  then  get  to  the  front  of  the  iris,  and  are  there  distri- 
buted as  white  radiating  filaments,  in  the  course  of  which 
may  be  observed  small  nodes,  supposed  by  Meckel  to  be 
Ganglions. 

The  trunks  of  the  Ciliary  nerves  depart  from  the  common 
form  of  such  bodies,  by  being  flattened  instead  of  cylindri- 
cal: they  are  small,  and  resemble  sewing  threads.  From 
their  number,  the  iris  is  probably  more  abundantly  supplied 
with  nerves  than  any  other  organ  of  the  body. 

The  Retina  forms  the  third  coat  of  the  eye,  and  lines  the 
internal  face  of  the  choroides  almost  in  its  whole  extent. 
The  optic  nerve  having  passed  through  the  sclerotica,  ter- 
minates on  its  inner  side  by  a bulb  or  button-like  end,  from 
the  circumference  of  which  the  retina  begins  to  expand,  and 
may  be  traced  satisfactorily  as  far  as  the  commencement  of 
the  ciliary  plaits  of  the  choroid  coat,  where  it  terminates  by 
a straight  edge,  somewhat  thickened.  Just  at  this  edge,  the 
retina  adheres  to  the  vitreous  humour,  and  is  supposed,  er- 
roneously by  some  anatomists,  as  Bichat  and  Monro,  to  be 
continued  on  to  the  circumference  of  the  lens.  Repeated 
dissections,  and  the  substantial  testimony  of  Soemmering,* 
have  satisfied  me  that  the  retina  cannot  be  fairly  traced  be- 
yond the  greater  circumference  of  the  impressions  made  on 
the  vitreous  humour  by  the  ciliary  striae  or  ridges.  When 
i the  eye  is  slightly  macerated,  the  retina  always  parts  from 
I the  vitreous  humour  at  this  point;  moreover,  when  its  struc- 
' ture  is  still  more  slightly  changed  by  freezing  and  then 


leones  Oculi  Humani. 


414 


NERVOUS  SYSTEM. 


thawing,  the  retina  manifests  a decided  preference  to  sepa- 
rate at  this  line,  and,  under  the  most  careful  dissection,  it 
is  very  difficult  to  prevent  it.  In  addition  to  these  conside- 
rations, there  is  a well  marked  change  of  colour  at  the  line 
mentioned;  in  front  of  this  line,  the  surface  is  transparent 
when  cleaned  from  the  pigmentum  nigrum,  whereas,  if  it 
were  retina,  it  should  be  the  colour  of  ground  glass,  as  is 
usual  in  the  dead  body;  also  the  veins  of  the  retina  never 
trespass  beyond  this  line,  but  are  seen  to  cruise  along  it. 

Most  anatomists  teach  that  the  retina  is  an  expansion  of 
the  optic  nerve.  Bichat  believed  that  the  latter  terminated 
at  the  bulb,  and  that  the  retina  was  another  part  of  the 
structure,  but  still  consisting  of  the  same  sort  of  nervous 
matter.  The  latter  opinion  is  probably  the  more  strictly 
correct,  because  there  is  more  pulpy  matter  in  a section  of 
the  retina  than  can  be  found  in  the  same  length  of  the  optic 
nerve;  also,  if  the  retina  were  simply  an  expansion  of  the 
nerve,  without  any  addition  of  matter  to  it,  it  should,  from 
its  hollow  globular  shape,  be  thinner  in  the  middle,  where 
it  is  most  expanded,  than  it  is  where  the  expansion  first 
begins,  at  the  bulb  of  the  optic  nerve. 

The  retina  does  not  adhere  to  the  choroid  coat,  neither 
to  the  vitreous  humour  which  it  encloses,  except  at  the  line 
mentioned;  when  this  line  of  attachment  is  broken,  the 
retina  quickly  collapses. 

The  texture  of  the  retina  is  extremely  soft  and  pulpy;  in 
the  living  state,  it  is  probably  perfectly  transparent,  but 
this  can  only  be  conjectured  from  the  readiness  with  which 
the  vessels  of  the  choroid  coat  can  be  seen  in  animals  des- 
titute of  pigmentum  nigrum.  It  is  composed  of  two  la- 
minae, of  which  the  external  is  medullary,  and  the  internal, 
or  that  next  to  the  vitreous  humour,  is  formed  of  a fine  re- 
ticulated cellular  membrane  with  blood  vessels  running 
through  it.  The  external  lamina  may  be  removed  by  a ca- 
mel’s hair  pencil,  or  by  slight  putrefaction  and  washing,  so 
as  to  leave  the  internal  entire.  The  celebrated  John  Hun- 
ter succeeded,  however,  in  separating  the  two  laminae  fairly 
from  each  other  and  preserving  them,  so  as  to  show  their 


THE  BALL  OP  THE  EVE. 


415 


difference.  This  specimen  may  be  considered  unique,  and 
every  way  deserving  of  the  source  from  which  it  pro- 
ceeded.* 

Exactly  in  the  axis  of  the  eye,  or  at  its  centre  posteriorly, 
consequently  about  a line  and  a half  from  the  outer  side  of 
the  bulb  of  the  optic  nerve,  Soemmering  discovered,  in  1791, 
a yellow  spot  of  a line  in  diameter,  with  a small  hole  in  its 
middle  made  by  a deficiency  of  medullary  matter.  From 
the  optic  nerve  there  goes,  towards  the  foramen,  a small 
fold  of  the  retina,  pointed  at  its  internal  end  and  obtuse  or 
bifurcated  externally.  Unless  the  eye  be  fresh,  these  things 
cannot  be  seen  distinctly,  for  the  evaporation  of  the  aque- 
ous humour  causes  a collapse  or  wrinkling  of  the  retina, 
which  obscures  them.  But  in  a perfectly  fresh  eye,  which 
is  well  managed,  they  may  be  seen  both  from  before  and  be- 
hind. It  was  thought,  for  some  time,  that  the  yellow  spot 
and  the  foramen  were  peculiarly  attributes  of  the  human 
being;  more  extended  and  successful  observation  has  cor- 
rected this  mistake,  by  detecting  them  in  several  classes  of 
animals. 

In  the  centre  of  the  optic  nerve,  where  it  enters  the  eye, 
is  a foramen  for  the  passage  of  the  artery  and  vein  belong- 
ing to  the  retina.  These  vessels  ramify,  by  a few  branches, 
on  the  internal  surface  of  the  membrane,  and  form  a sort  of 
circle  surrounding  the  yellow  spot.  Neither  the  branches 
of  arteries  or  veins  communicate  with  those  of  the  choroides. 
and,  as  observed,  never  go  beyond  what  we  just  considered 
as  the  anterior  margin  of  the  retina,  but  rather  run  along  it. 

Interposed  between  the  retina  and  the  choroides,  is  a 
most  delicate  serous  membrane  lately  discovered  by  Mr.  Ja- 
cobs, Demonstrator  of  Anatomy  in  Trinity  College,  Dub- 
lin. By  preparing  the  I’etina  in  the  usual  way,  and  then 
floating  the  eye  in  a saucer  of  water,  this  membrane  may 
be  turned  down  with  the  handle  of  a knife  from  the  optic 
nerve  to  the  termination  of  the  retina.  It  is  supposed  to 

* The  fact  was  communicated  to  me  by  Dr.  Physick,  who  stacked  under 
Mr.  Hunter,  and  frequently  saw  the  preparation. 


416 


NERVOUS  SYSTEM. 


be  the  seat  of  the  ossifications  which  are  sometimes  met 
with  in  the  eye. 

Humours  of  the  Eyeball. 

The  Vitreous  Humour  {Humor  Vitreus,  Corpus  Vi- 
treum)  occupies,  with  the  exception  of  a very  small  part 
just  behind  the  iris,  the  whole  of  the  space  posterior  to  the 
latter.  It  is  therefore  very  nearly  globular;  is  in  contact 
the  greater  part  of  its  extent  with  the  retina,  at  least  as  far 
as  the  latter  membrane  proceeds;  in  front  it  is  in  contact 
with  the  crystalline  humour,  and  from  the  margin  of  the  re- 
tina to  the  circumference  of  the  lens  it  is  in  contact  with  the 
ciliary  body,  meaning  thereby  the  ciliary  strise  and  pro- 
cesses of  the  choroides. 

Two  parts  compose  the  vitreous  humour, — the  hyaloid 
membrane  and  a thin  fluid.  In  a natural  state  they  are  per- 
fectly transparent,  and  therefore  cannot  be  readily  distin- 
guished from  each  other;  but  by  immersion  in  spirits  of 
wine  the  membranous  portion  is  brought  to  the  colour  of 
ground  glass,  and  may  then  be  studied  very  advantageous- 
ly. The  membrane,  though  extremely  delicate,  is  gene- 
rally strong  enough  to  permit  the  whole  vitreous  body 
to  be  suspended  in  the  air  by  a thread  passed  through  it, 
and  it  may  also  be  momentarily  held  up  with  a pair  of 
forceps. 

The  Tunica  Hyaloidea  may  be  traced  as  a complete  cap- 
sule, forming  the  periphery  of  the  vitreous  humour;  and 
from  the  internal  face  of  this  capsule  there  proceeds  a great 
number  of  partitions  dividing  the  whole  cavity  into  cells  of 
various  magnitudes  and  forms.  Some  anatomists,  who  have 
frozen  the  eye  and  then  picked  out  the  pieces  of  ice  from 
the  cells,  have  got  the  idea  of  their  being  all  cuneiform,  and 
of  their  edges  pointing  forwards.  Our  preparations  in  the 
anatomical  cabinet  are  perfectly  satisfactory  in  exhibiting 
the  existence  of  an  arrangement  of  cells,  but  do  not  mani- 
fest a regular  cuneiform  shape  in  them. 

When  the  capsule  of  the  tunica  hyaloidea  has  got  to  the 


THE  BALL  OF  THE  EYE. 


417 


distance  of  two  lines  or  thereabouts,  from  the  circumference 
of  the  lens,  it  divides  into  two  laminae,  which  reunite  at 
the  circumference  of  the  lens.  They  then  divide  again, 
and  one  goes  before  the  capsule  of  the  lens,  and  the  other 
behind  it.  The  space  between  the  two  layers,  around  the 
circumference  of  the  lens,  is  the  canal  of  Petit,  and  is  that 
part  of  the  tunica  hyaloidea  which  is  impressed  by  the  cilia- 
ry striae  and  ridges  of  the  choroides.  At  intervals,  pass- 
ing in  a radiated  manner,  from  the  exterior  to  the  interior 
circumference  of  the  canal,  there  is  a sort  of  shortening  or 
constriction  of  it,  producing  partial  septa  in  its  cavity;  so 
that  when  the  canal  is  inflated,  it  seems  to  consist  of  a series 
of  small  cells,  arranged  circularly.  The  cells  of  the  colon 
will  give  some  idea  of  this  arrangement,  though  they  are 
produced  in  an  entirely  difierent  manner. 

The  fluid  part  of  the  vitreous  humour,  by  analysis,  gives 
out  98.40  W’ater,  .16  albumen,  and  the  remainder  is  saline. 
In  consequence  of  the  very  small  quantity  of  albumen  in 
it,  neither  acids  or  heat  coagulate.it  to  a striking  degree. 

The  vitreous  humour  is  supplied  with  a branch  from  the 
central  artery  of  the  retina.  This  branch  does  not  convey 
red  blood,  but  only  serum,  except  in  the  fcetal  eye.  It 
may  be  injected,  at  almost  any  age,  with  size,  coloured 
with  vermilion;  but  is  then,  of  course,  put  very  much  on 
the  stretch.  It  has  been  well  described  by  Zinn.  It  pe- 
netrates the  vitreous  humour  near  the  optic  nerve,  and  is 
disseminated  by  very  fine  branches  on  the  peripher}^,  and 
on  the  internal  cellular  structure  of  the  tunica  hyaloidea. 
M.  J.  Cloquet  has  described  particularly  one  branch,  which, 
running  through  the  centre  of  the  vitreous  humour,  in  an 
appropriate  canal,  is  spent  by  small  ramifications  upon  the 
posterior  part  of  the  capsule  of  the  lens. 

Some  anatomists*  speak  of  a fluid  between  the  tunica 
hyaloidea  and  the  retina:  when  it  does  exist,  it  in  all  pro- 
bability is  the  fluid  of  the  vitreous  humour,  which  has 
strained  through  the  tunica  hyaloidea  after  death. 

* Bichat,  Anat.  Descrip, 

VoL.  II 53 


41S 


NERVOUS  SYSTEM. 


The  Lens  {Lens  Crystallina)  or  the  Crystalline  Hu- 
mour, as  it  is  very  generally  called,  is  placed  immediately 
behind  the  pupil,  in  a depression  on  the  front  of  the  vitre- 
ous humour.  Its  shape  is  that  of  a doubly  convex  lens,  of 
which  the  posterior  convexity  is  greatest,  being  the  section 
of  a sphere  whose  diameter  is  from  four  to  five  lines,  while 
the  anterior  convexity  is  in  the  proportion  of  a sphere  of 
from  six  to  nine  lines.  The  usual  breadth  of  the  lens  is 
about  three  and  a half  lines.  It  varies  its  shape  in  a re- 
markable degree  at  the  different  periods  of  life;  immediate- 
ly after  birth  it  is  spheroidal,  in  about  six  years  afterwards 
its  lenticular  shape  is  well  marked,  and  subsequently  it  be- 
comes more  flat  and  thin. 

The  Lens  naturally  is  perfectly  transparent.  In  the 
greater  part  of  its  thickness  it  has  the  consistence  of  half 
dissolved  glue,  but  its  centre  is  much  more  solid;  this 
change,  however,  is  effected  successively.  When  it  is  sub- 
jected to  the  mineral  acids,  to  heat,  to  alcohol,  and  several 
other  agents,  it  becomes  much  more  solid  throughout;  it 
may  then  be  separated,  like  an  onion,  into  a series  of  con- 
centric lamellae,  subdivisible  into  longitudinal  fibres.  Be- 
sides these  there  are  fibres  more  or  less  oblique  which  hold 
the  lamellae  together.  These  arrangements  prevail  from 
the  centre  to  the  circumference  of  the  lens;  and  between 
its  laminae  there  is  a diaphanous  humour  resembling  that 
between  it  and  its  capsule,  * 

The  Lens  is  invested  by  a capsule  which  is  a complete 
sac,  having  exactly  its  shape,  but  separated  from  it,  to  a 
very  inconsiderable  extent,  by  the  transparent  humour  just 
alluded  to,  called  the  Liquor  Morgagni.  The  capsule  is 
covered  in  front  by  a layer  of  the  tunica  hyaloidea  adhering 
very  closely  to  it,  but  which,  in  one  instance,  I was  enabled 
to  peel  off  partially  in  the  eye  of  a sheep,  from  one  side  to 
the  other.  The  capsule  is  covered,  in  like  manner,  on  its 
posterior  face,  by  the  tunica  hyaloidea,  but  the  two  may  be 
separated  there  more  easily,  according  to  the  observations 
of  Bichat.  Some  of  the  most  distinguished  continental 


* J.  F.  Meckel, 


THE  BALL  OP  THE  EYE. 


419 


anatomists  are  decidedly  in  favour  of  the  capsule  of  the 
crystalline  being  a complete  bag;  but  it  is  rather  unsettled 
whether  the  exterior  margin  of  the  capsule  bounds  the  les- 
ser circumference  of  the  canal  of.  Petit,  or  whether  the  two 
layers  of  the  tunica  hyaloidea  unite  previously  at  the  cir- 
cumference of  the  capsule.  The  latter  seems  to  be  the  opi- 
nion of  M.  J.  Cloquet.  Dr.  Physick,  in  some  cases  of 
membranous  cataract,  has  succeeded  in  drawing  out  the  cap- 
sule entire,  so  as  to  exhibit  its  whole  extent  when  it  is  float- 
ed in  water. 

The  capsule  in  front  of  the  lens  is  much  thicker  than  the 
tunica  hyaloidea,  and  its  difierence  of  character  from  the 
latter  appears  to  me  to  be  very  strongly  marked.  For  not- 
withstanding its  immersion  in  spirits  of  wine,  it  retains  its 
transparency;  it  is  hard  and  elastic,  and  when  clipped  with 
the  scissors,  gives  nearly  tbe  same  sensation  as  the  thin 
paring  of  a finger  nail  would;  or,  as  has  been  observed  by 
Haller,  it,  in  this  respect,  resembles  the  cornea.  The  ana- 
logy with  the  cornea  ceases,  however,  at  this  point;  for  the 
cornea  has  always  so  much  albuminous  matter  in  it  as  to  be 
rendered  turbid  when  it  is  immersed  in  alcohol.  The  pos- 
terior section  of  the  capsule  of  the  lens,  is  not  so  well  marked 
either  by  its  thickness  or  specific  characters  as  the  anterior, 
yet  our  preparations  in  the  University  demonstrate  its  ex- 
istence equally  as  conclusively.  It  is  more  assimilated  to 
the  nature  of  the  tunica  hyaloidea. 

In  the  injected  fostal  eye,  the  artery  of  the  tunica  hya- 
loidea which  comes  from  the  central  one  of  the  retina,  is 
seen  to  furnish  several  minute  ramifications  to  the  posterior 
face  of  the  lenticular  capsule;  some  of  its  branches  also  go 
to  the  front  of  the  capsule,  but  the  latter  part  is  furnished 
principally  by  arterioles  from  the  ciliary  body  of  the  cho- 
roides.  The  two  sets  of  arteries  anastomose  with  each 
other,  some  of  the  latter  are  also  spent  upon  the  memhrana 
pupillaris. 

The  point  is  yet  doubtful  whether  any  of  these  arteries 
penetrate  into  the  body  itself  of  the  crystalline  humour. 
Ruysch,  Albinus,  and  Haller,  assert  the  fact  of  their  having 


-120 


NERVOUS  SYSTEM. 


seen  and  injected  them  in  the  human  species  and  in  ani- 
mals, and  J.  F.  Meckel  admits  their  testimony.  Yet  there 
are  not  many  anatomists  who  can  corroborate  it  by  their 
personal  observations.  It  is  sufficiently  reasonable  to  admit 
it,  for  without,  we  cannot  conveniently  account  for  the 
growth  and  nutrition  of  the  lens,  as  well  as  the  morbid 
changes  which  occur  in  it.  It  should  be  observed  that  if 
this  vascular  connexion  does  exist  it  is  a very  weak  one; 
for  the  lens  seems  to  be  simply  surrounded  by  its  capsule 
without  adhering  to  it. 

Some  veins  which  discharge  into  the  veins  of  the  choroid 
coat  have  been  observed  by  Walter*  on  the  posterior  part 
of  the  capsule.  It  should  be  continually  borne  in  mind 
that  neither  the  arteries  nor  veins  of  the  healthy  crystalline, 
nor  of  its  capsule  convey  red  blood;  in  which  respect  they 
correspond  with  the  hyaloidea,  for  if  this  were  the  case,  vi- 
sion would  be  very  much  disordered  by  if.  It  may  be  that 
the  moats  or  specks  seen  in  ophthalmia  arise  from  the 
grosser  particles  of  the  blood,  getting  into  these  serous  ves- 
sels by  the  dilatation  of  the  latter. 

The  Lens  and  its  Capsule  are  devoid  of  nerves,  at  least 
none  have  been  as  yet  traced  into  them. 

The  Aqueous  Humour  {Humor  Jiquosus)  occupies  the 
space  which  is  between  the  anterior  face  of  the  crystalline 
capsulej  and  the  posterior  face  of  the  cornea.  This  space 
is  unequally  divided  by  the  iris  into  two  chambers,  of 
which  the  anterior  is  in  front  of  the  latter  membrane,  and 
the  posterior  behind  it.  In  consequence  of  the  convexity 
of  the  lens,  the  posterior  chamber  has  but  very  little  depth 
just  behind  the  pupil;  but  its  space  is  augmented  at  the  cir- 
cumference of  the  crystalline,  so  as  to  leave  room  for  the 
floating  of  the  ciliary  processes  and  for  the  motions  of  the 
iris.  The  posterior  chamber  is  therefore  a circular  vacuity; 
the  centre  of  which,  from  the  projection  of  the  centre  of 
the  crystalline,  has  scarcely  any  appreciable  depth.  The 
anterior  chamber  in  its  shape  resembles  the  segment  of  a 


* I)e  Oculis.  Berlin,  1778. 


THE  BALL  OF  THE  EYE. 


4:21 


sphere:  its  depth  depends  essentially  on  the  size  and  the 
projection  of  the  cornea. 

The  aqueous  humour  is  perfectly  transparent,  and  almost 
as  fluid  as  water.  The  analysis  of  Berzelius  exhibits  98 
parts  of  water,  1 of  liydrochlorate  and  lactate  of  lime,  .75 
of  some  animal  matter  soluble  in  water,  and  a very  small 
quantity  of  albumen.  F rom  the  latter  circumstance  it  will 
be  understood  how  this  fluid  refuses  to  coagulate  on  the  ad- 
dition of  alcohol  or  of  mineral  acids  to  it,  and  is  only  ren- 
dered in  a very  slight  degree  turbid'by  them.  The  rapidi- 
ty of  the  exhalation  of  this  fluid  is  remarkable:  when  the 
whole  of  it  is  lost  in  the  operation  for  cataract,  it  is  regene- 
rated in  from  twenty-four  to  thirty-six  hours.  Its  source 
has  been  sought  for  in  suppositious  canals  and  glands,  but 
the  more  probable  opinion  is,  that  it  may  come  from  any 
or  all  of  the  exhalent  arteries  of  the  chambers  of  the  eye. 

Like  the  other  two  humours  of  the  Eye,  the  aqueous  is 
furnished  with  a capsule,  but  whether  it  is  complete  or  not 
is  yet  undetermined.  By  immersing  the  eye  in  hot  water, 
or  in  alcohol,  this  capsule  may  be  readily  detected  on  the 
posterior  face  of  the  cornea,  and  to  the  greater  circumfe- 
rence of  the  iris;  it  may  even  be  traced  for  some  distance 
on  the  front  surface  of  the  latter.  Some  of  the  French 
anatomists,  as  Demours,*  Descemet,  and  J.  Cloquet,  have 
asserted  that  it  continued  also  through  the  pupil  to  line  the 
posterior  chamber.  An  opinion  like  this,  from  the  extreme 
tenuity  of  the  parts,  must  be  rather  the  result  of  conjec- 
ture than  of  accurate  observation;  it  has  therefore  never 
found  its  way  with  full  force  into  the  writings  of  anato- 
mists. The  condition  of  the  pigmentum  nigrum  on  the 
posterior  face  of  the  iris,  and  on  the  ciliary  processes,  would 
seem  to  be  an  objection  to  the  existence  of  this  capsule  in 
the  posterior  chamber  of  the  eye.  But  if  it  really  does  ex- 
ist there,  as  is  pretended  by  M.  Portal,  who  supposes  it  to 
be  derived  from  the  tunica  hyaloidea,  its  structure  is  incom- 
parably more  delicate  than  that  part  on  the  cornea,  and  in- 
deed is  merely  glutinous. 


* Demours,  Lettre,  1767. 


NERVOUS  SYSTEM. 


The  Chambers  of  the  Eye,  till  the  seventh  month  of 
foetal  existence,  and  sometimes  later,  are  perfectly  separated 
from  each  other  by  the  Membrana  Pupillaris,  called  so  from 
its  position  in  the  pupil  of  the  iris.  It  was  discovered  in 
1740,  by  Wachendorf,  and  is  sometimes  called  after  his 
name.  It  is  a thin,  delicate,  and  transparent  membrane, 
which  is  stretched  across  the  pupil  from  its  circular  margin, 
and  may,  by  its  colour  be  readily  distinguished  from  the 
iris,  when  it  has  been  made  somewhat  turbid  by  alcohol. 

The  Membrana  Pupillaris  consists,  according  to  M.  J. 
Cloquet,*  of  two  laminae  placed  back  to  back,  of  which  the 
foremost  is  a continuation  of  the  membrane  which  lines  the 
anterior  chamber  of  the  eye,  and  the  hindmost,  of  that  which 
lines  the  posterior  chamber.  According  to  this,  it  may  be 
noticed  that  each  chamber  has  its  distinct  capsule.  This 
membrane  is  very  vascular;  some  of  its  arteries  are  those 
which  subsequently  form  the  internal  arterial  circle  of  the 
iris,  and  they  radiate  from  the  circumference  to  the  centre 
of  the  membrane;  others  come  directly  from  the  long  ci- 
liary arteries,  and  others  again  from  the  arteries  of  the  crys- 
talline capsule.  These  several  vessels  are  found  principal!}’' 
on  its  posterior  face.  Its  veins  have  not  been  observed. 

This  membrane  .first  shows  itself  about  the  third  month 
of  fcEtal  existence,  and  is  most  perfect  at  the  seventh;  from 
the  latter  period  it  begins  to  decline,  by  disappearing  from 
the  centre  to  the  circumference.  At  the  ninth  month  it 
consists  only  in  a few  loose  flocculent  masses  adhering  to 
the  pupil.  M.  J.  Cloquet  has  ascertained  that  its  vessels  do 
not  participate  in  its  destruction,  but  that  the  arches  which 
they  form  are  retracted  to  the  margin  of  the  pupil,  and  there 
form  the  lesser  arterial  circle  of  the  iris.  From  the  obser- 
vations of  Drs.  Jacob  and  Tiedemann,  it  appears  that  traces 
of  the  membrana  pupillaris  exist  for  ten  or  fifteen  days  after 
birth.  The  latter,  in  one  case,  injected  its  vessels  in  a foetus 
at  full  term.t 

'*  Journal  Universelle  des  Sc.  Med.  Par.  1818.  Mem.  sur  la  memb.  ])U- 
pill,  Paris,  1818. 

f Am.  Med.  Jour.  vol.  i.  p.  192. 


. THE  EXTERNAL  EAR. 


423 


CHAPTER  II. 

OF  THE  EAR. 

Tee  ear,  the  organ  of  hearing,  is  placed  principally  with- 
in the  petrous  portion  of  the  temporal  bone,  and  consists  in 
the  External  Ear,  the  Tympanum,  and  the  Labyrinth. 

SECT.  I. OP  THE  external  EAR. 

The  position  of  this  portion  of  the  organ  is  familiar  to 
every  one.  It  is  useful  in  collecting  the  rays  of  sound,  and 
in  conveying  them  to  the  more  internal  parts.  It  is  formed 
by  the  structure,  exterior  to  the  petrous  bone,  called,  in 
common  language,  the  Ear;  and  by  a canal  which  leads  in- 
ternally to  the  tympanum.  The  basis  of  this  portion  is  cai’- 
tilaginous,  on  which  circumstance  it  depends  for  the  per- 
manency of  its  shape. 

The  ear,  of  common  language,  is  divided  into  two  por- 
tions, Pinna*  and  Lobus:  the  former  is  the  most  extensive, 
as  it  comprehends  all  the  cartilaginous  portion;  the  latter  is 
attached  to  the  inferior  margin  of  the  former,  and,  having 
no  cartilage  in  its  composition,  is  soft  and  pendulous. 

In  the  centre  of  the  external  ear  is  a deep  depression  called 
the  Concha;  in  the  bottom  of  it  is  the  orifice  of  the  canal 
leading  to  the  tympanum,  and  called  Meatus  Auditorius 
Externus.  The  circumference  of  the  pinna  is  convoluted 
into  a scroll  called  the  Helix,  and  commences  just  above  the 
meatus  by  a ridge.  This  ridge  divides  the  concha  into  two 
unequal  cavities,  of  which  the  lower  is  the  larger.  The 
scroll  becomes  gradually  less  prominent,  till  it  terminates 
at  the  posterior  inferior  part  of  the  pinna,  in  the  lobus. 

The  Antihelix  is  the  slightly  curved  and  vertical  emi- 
nence in  the  middle  of  the  pinna;  its  lower  part  forms  the 

* From  some  resemblance  to  a ceitain  shell  fish. 


424 


NERVOUS  SYSTEM. 


posterior  boundary  of  the  concha,  and  its  upper  part  bifur- 
cates into  two  small  ridges,  between  which  there  is  a de- 
pression called  the  Scapha.  Between  the  antihelix  and  the 
posterior  half  of  the  helix,  is  an  oblong  depression  called  the 
Fossa  Innominata. 

The  Tragus  is  a cartilaginous  elevation  of  the  pinna  placed 
in  front  of  the  concha,  and  inclining  somewhat  over  it;  op- 
posite to  it,  at  the  inferior  part  of  the  concha,  is  the  Anti- 
tragus Cartilage. 

The  cartilage  upon  which  the  external  ear  depends  for  its 
shape  is  of  a thickness  very  nearly  uniform,  of  course  the 
ridges  and  depressions  on  its  exterior  surface  have  corre- 
sponding depressions  and  ridges  on  the  side  next  to  the 
head.  It  is  interrupted  at  several  places  by  fissures;  for 
example,  there  is  one  of  considerable  size  filled  up  with 
ligamentous  matter,  which  separates  the  upper  margin  of 
the  tragus  from  the  beginning  of  the  helix;  there  is  another 
between  the  lower  extremity  of  the  antihelix  and  the  anti- 
tragus. In  the  tragus,  there  are'two  and  sometimes  thi;ee 
small  narrow  ones,  said,  by  Santorini,  to  be  filled  with  mus- 
cular fibres;  but  the  latter  assertion  does  not  correspond 
with  the  observations  of  subsequent  anatomists,  as  the  mat- 
ter appears  fibrous. 

The  external  ear  is  united  to  the  side  of  the  head  by  three 
ligaments.  The  anterior  arises  from  the  root  of  the  zygo- 
matic process  above  the  articulation  of  the  lower  jaw,  and 
is  inserted  into  the  pointed  production  of  cartilage  on  the 
fore  part  of  the  helix.  The  posterior  arises  from  the  swell 
of  the  temporal  bone,  which  runs  into  the  front  margin  of 
the  base  of  the  mastoid  process,  and  is  inserted  into  the  con- 
vex side  of  the  concha,  at  the  beginning  of  the  meatus  audi- 
torius.  The  superior  arises  from  the  temporal  aponeurosis, 
and  is  inserted  into  the  upper  part  of  the  concha.  These 
ligaments  lie  immediately  below  the  muscles  destined  to 
move  the  ear. 

The  Meatus  Auditori.us  Externus  is,  in  the  adult,  an  inch 
in  length,  reckoning  from  its  external  orifice  to  the  mem- 


THE  EXTERNAL  EAR. 


425 


brane  of  the  tympanum,  which  closes  it  inwardly.  It  is 
about  three  lines  in  diamoter,  is  rather  oval  than  cylindrical, 
and  somewhat  smaller  in  the  middle  than  at  either  of  its 
extremities.  It  runs  i'lwards,  with  a slight'inclination  for- 
wards; the  exterior  half  is  formed  by  the  cartilage  of  the 
pinna,  and  the  internal  half  by  the  temporal  bone;  it  departs 
from  the  horizontal  course,' in  .being  curved  at  its  middle 
where  the  two  sections  join.  This  curvature  has  its  con- 
vexity upwards,  so  that  when  we  wish  to  look  to  the  bot- 
tom of  the  canal,  the  external  ear  must  be  pulled  upwards 
and  backwards. 

The  cartilaginous  portion  of  the  meatus  auditorius  is 
formed  by  a triangular  piece,  springing  from  the  base  of  the 
tragus  and  from  the  inferior  anterior  part  of  the  concha. 
This  portion  is  nearly  a tube,  but  is  interrupted  above  and 
behind  by  the  intervention  of  a dense  fibrous  tissue,  con- 
tinuous with,  and  indeed  the  same  with  that  which  joins 
the  helix  and  the  tragus.  The  cerebral  margin  of  the  car- 
tilaginous meatus  forms  a point  below,  and  adheres  by  liga- 
ment very  closely  to  the  asperities  on  the  margin  of  the 
bony  meatus.  If  there  were  no  fissures  in  the  external  ear, 
it  would,  therefore,  be  almost  inimoveable. 

The  skin  covering  the  external  ear,  is  more  delicate  than 
in  most  other  parts  of  the  surface  of  the  body.  Its  sebace- 
ous glands  or  follicles  are  very  abundant,  and  in  infants  se- 
crete freely  their  peculiar  fluid.  When  a slight  inflammation 
occurs,  this  discharge  is  frequently  purulent  without  ero- 
sion. A duplication  of  the  skin,  containing  a delicate  gra- 
.nulated  adeps  with  some  fibrous  rriatter,  constitutes  the  lobe 
of  the  ear. 

The  skin,  after  lining  the  concha,  descends  into  the  mea- 
tus auditorius  and  lines  it  also,  as  well  as  the  external  face 
of  the  membrane  of  the  tympanum.  It  adheres  moderately 
to  the  cartilaginous  part  of  the  tube,  and  more  tenaciously 
to  its  fibrous  portions;  between  it  and  the  latter,  are  found 
many  small  reddish  bodies,  generally  oval,  the  G-landulse 
VoL.  II.— 54 


NERVOUS  SYSTEM. 


1.2  G 

Ceruminosae,*  from. which  proceeds  the  earwax.  The  skin 
is  extremely  thin  in  the  bony  meatus,  adheres  closely  to  its 
periosteum,  and  is  highly,  sensible;  where  it  forms  the  ex- 
terior layer  of  the  membrane  of  the  tympanum,  it  may  be 
detached  from  the  latter  with  the  slightest  force,  and  seems 
to  be  converted  almost  entirely  into  cuticle.  A slight  ma- 
ceration or  incipient  putrefaction-  frequently  enables  one 
to  draw  the, cuticle  out  entire  from  the  meatus,  so  that  it 
looks  in  shape  like  the  finger  of  a small  glove. 

The  dermoid  lining  of  the  meatus  is  studded  with  fine 
hairs,  which  serve  to  keep  out  small  bodies  that  may  be 
floating  in  the  air.  A considerable  number  of  'small  pores 
are  also  seen  in  it,  which  are  the  orifices  of  the  ducts  of  the 
ceruminous  glands.  The  discharge  of  the  latter,  when  first 
secreted,  is  thin  and  white:  by  evaporation  it  becomes  thick 
and  ’yellow,  and  by  accumulating  obstructs  the  passage. 

There  are  several  small  muscles  situated  on  the  external 
ear,  which  are  for  the  most  part  so  feebly  developed  that 
they  cannot  always  be  found,  and  when  they  do  exist  they 
seem  more  like  the  rudiments  of  what  is  well  marked  in 
animals,  than  intended  for  a special  purpose  in  the  human 
body. 

1.  The  Helicis  Major  is  an  oblong  fasciculus,  situated  on 
the  front  of  the  helix.  By  its  lower  end  it  is  attached  to  the 
point  of  cartilage  on  the  front  of  the  helix,  and  its  other  ex- 
tremity extends  to  the  top  of  the  latter. 

2.  The  Helicis  Minor  is  a small  square  fasciculus,  also  on 
the  front  of  the  helix,  between  the  folded  margin  of  the  lat- 
ter and  the  inferior  half  of  the  helicis  major. 

3.  The  Tragicus  is  a square  fasciculus,  on  the  front  sur- 
face of  the  tragus,  near  its  margin:  its  upper  extremity  some- 
times runs  into  the  helicis  major. 

4.  The  Antitragicus  is  a small  oblong  fasciculus,  which 


Duverney,  (Euvres  Anotomiques. 


THE  TYMPANUM. 


427 


arises  from  the  upper  extremity  of  the  antitragus,  and  going 
upwards  it  is  inserted  into  the  inferior  extremity  of  the  anti- 
helix. 

5.  The  Transversus  Auriculce  is  on  the  cerebral  surface 
of  the  pinna.  It  arises  from  the  prominence  of  the  con- 
cha, and  is  inserted  into  the  hollow  dorsum  of  the  anti- 
helix. 

There  are  some  other  muscles  which  may  be  uniformly 
found  and  are  intended  to  move  the  external  ear  upon  the 
side  of  the  head,  though  from  the  want  of  exercise  there 
are  very  few  individuals  capable  of  making  them  contract. 
They  are 

1.  The  Attollens  Auriculse  is  placed  on  the  side  of  the 
head  beneath  the  integuments:  it  is  a broad,  thin,  and  some- 
what triangular  muscle,  which  arises  from  the  inferior  mar- 
gin of  the  tendon  of  the  occipito-frontalis,  and  from  the 
temporal  aponeurosis.  It  becomes  narrower  in  its  descent, 
and  is  inserted  tendinous  into  the  elevation  of  the  pinna, 
corresponding  with  the  scapha. 

Its  name  implies  its  action  to  be  that  of  raising  the  pinna. 

2.  The  Retrahens  Auriculae,  consists  in  two  or  three  ob- 
long fasciculi,  placed  parallel,  and  one  above  the  other.  It 
arises  from  the  mastoid  portion  of  the  temporal  bone,  above 
the  mastoid  process,  and  is  inserted  tendinous  into  the  con- 
vex side  of  the  concha  near  the  meatus  auditorius. 

^It  draws  the  pinna  backwards. 

3.  The  Anterior  Auriculae  is  a small  quadrangular  slip, 
just  above  the  root  of  the  zygomatic  process.  It  arises 
from  the  temporal  fascia,  and  is  inserted  tendinous  into  the 
fore  part  of  the  helix  just  above  its  root. 

It  draws  the  pinna  forwards  and  upwards. 


\2S 


NERVOUS  SYSTEM. 


SECT.  II. — OF  THE  TYMPANUM. 

The  Tympanum  is  the  middle  portion  of  the  organ  of 
hearing,  being  interposed  hetween  the  meatus  auditorius 
and  the  labyrinth.  Its  depth  is  about  three  lines,  its  ante- 
ro-posterior  diameter  about  six,  and  its  vertical  diameter 
rather  more,  though  from  the  general  inequality  of  the  ca- 
vity, and  its  communication  with  adjoining  cavities  it  is  not 
easy  to  fix  upon  very  precise  measurements. 

The  Membrana  Tympani,  is  a complete  membranous 
septum,  interposed  between  the  meatus  externus  and  the 
tympanum.  It  is  placed  very  obliquely,  so  that  its  upper 
edge  inclines  outwards,  and  its  under  edge  inwards;  the  lat- 
ter therefore  forms  a very  acute  entering  angle  with  the  in- 
ferior part  or  floor  of  the  meatus,  and  gives  to  that  portion 
of  the  meatus  an  additional  length,  which  renders  it  diffi- 
cult to  see  to  its  bottom.  The  membrane  of  the  tympa- 
num is  nearly  circular,  and  has  its  circumference  adhering 
very  closely  to  the  external  orifice  of  the  tympanum.  It 
is  slightly  tense,  and  has  its  middle  drawn  inwards  by  being 
attached  to  the  handle  of  the  malleus. 

The  membrana  tympani  consists  of  four  laminse;  the  two 
exterior  of  which  being  the  cuticle  and  the  cutis  vera, 
which  line  the  meatus  auditorius,  are  easily  detached,  as 
mentioned  before,  and  seem  scarcely  to  adhere  to  the  layer 
below.  The  third  layer  is  the  proper  membrane,  and  is 
distinguished  by  its  dryness  and  by  its  transparency.  Sir 
Everard  Home  was  enabled  to  detect  radiated  muscular 
fibres,  forming  it  in  the  elephant.*  In  the  human  subject 
its  fibrous  character  is  best  seen  on  its  internal  face;  but  the 
radiated  arrangement  is  not  so  distinct.  Caldani  considers 
it  as  formed  by  filaments,  decussating  each  other  at  right 
angles,  and  intermixed  with  blood  vessels. t The  internal 
layer  is  a continuation  of  the  lining  membrane  of  the  tym- 

* Philosophical  Transactions,  for  1800.  London. 

t Plate  XCVm.  Anat, 


THE.  TYMPANUM. 


429 


panum;  it  is  separated  with  some  difficulty,  owing  to  its  te- 
nuity. 

The  proper  membrane  of  the  tympanum,  when  success- 
fully injected,  exhibits  a high  degree  of  vascularity*  though 
in  its  natural  state  but  very  few  red  blood  vessels  are  seen 
in  it. 

The  floor  of  the  tympanum,  or  the  side  next  to  the  laby- 
rinth, presents  an  unequal  surface.  In  its  middle  is  a well 
marked  rising,  the  Promontory,  {Promontorium)  formed 
by  one  end  of  the  labyrinth.  Just  above  the  superior  mar- 
gin of  this  prominence,  near  its  centre,  is  an  oval  opening, 
called  from  its  shape,  Foramen  Ovale,  or  Fenestra  Ovalisj 
having  its  long  diameter  horizontal,  its  superior  margin 
rounded  or  concave,  and  its  inferior  straight.  At  the  pos- 
terior inferior  part  of  the  promontory  is  another  opening, 
which  though  somewhat  triangular,  is  called  the  Foramen 
Rotundum,  or  Fenestra  Rotunda,  and  in  the  dried  bone 
leads  to  the  cochlea,  but  is  naturally  stopped  by  the  lining 
membrane  of  the  tympanum.  According  to  M.  Ribes,  this 
membranous  plug  has  also  two  other  layers,  an  internal  one, 
the  continuation  of  what  lines  the  cochlea,  and  a middle 
one,  which  is  peculiar.  In  these  respects  there  is  a corres- 
pondence with  the  membrana  tympani. 

The  Eminentia  Pyramidalis  is  a small  conical  eminence 
projecting  from  the  posterior  part  of  the  tympanum,  on  a 
line  with  the  fenestra  ovalis.  It  is  hollow,  contains  a mus- 
cle, and  communicates  at  the  other  end  with  the  Canal  of 
Fallopius.  Lower  down  and  more  externally,  there  is  a 
small  orifice,  {Jipertura  Chordse)  through  which  the  nerve 
called  Chorda  Tympani  passes. 

The  Mastoid  Portion  of  the  Temporal  bone,  in  the  adult, 
abounds  in  large  cells  or  sinuses,  which  communicate  freely 
with  one  another.  They  are  distinct  from  the  diploic  struc- 
ture of  the  bone,  as  they  contain  no  meditullium,  and  are 

* Ruyschii,  Epist.  Anat.  Probl.  viii.  Anatomical  Museum  of  Univer. 


430 


NERVOUS  SYSTEBX. 


lined  by  a continuation  of  the  internal  membrane  of  the 
tympanum,  which  is  extremely  thin  upon  them.  The  ori- 
fice of  communication  between  these  cells  and  the  tympa- 
num is  placed  at  the  superior  posterior  part  of  the  latter;  it 
is  rough  and  irregular,  and  partially  occupied  by  the  short 
leg  of  the  incus.  Just  in  front  of  this  opening,  the  cavity 
of  the  tympanum  is  extended  vertically,  for  the  purpose  of 
accommodating  the  body  of  the  malleus  and  of  the  incus, 
whereby  they  are  in  a great  degree  concealed,  unless  the 
corresponding  margin  of  the  tympanum  be  cut  away. 

At  the  fore  part  of  the  tympanum  is  the  Eustachian  Tube, 
which  runs  for  six  or  eight  lines  in  the  substance  of  the  pe- 
trous bone,  near  its  exterior  margin,  and  then  terminates  in 
a cartilaginous  and  membranous  portion,  which  communi- 
cates with  the  pharynx  at  the  posterior  nares.  The  latter- 
extremity  of  the  Eustachian  Tube  is  placed  on  a line  with 
the  posterior  end  of  the  inferior  spongy  bone.  Its  orifice  is 
rounded  or  oval,  is  large  enough  to  admit  the  tip  of  the  lit- 
tle finger,  and  reposes  against  the  side  of  the  internal  ptery- 
goid process  of  the  sphenoid  bone.  • Though  almost  within 
the  precincts  of  the  posterior  naris,  this  orifice  is  to  be  con- 
sidered,as  opening  into  the  pharynx. 

This  canal,  in  its  whole  length,  measures  nearly  two 
inches,  and,  with  the  exception  of  the  portion  in  the  pe- 
trous bone,  is  cartilaginous  and  membranous.  The  carti- 
lage is  a single,  thick,  triangular  plate,  flat,  and  adhering 
by  one  of  its  edges  to  the  pterygoid  process.  The  under 
part  of  the  tube  is  membranous,  thin,  and  affords  attach- 
ment to  some  of  the  muscles  of  the  soft  palate.  Its  course 
is  nearly  horizontal,  backwards  and  outwards. 

It  is  lined  in  its  whole  extent,  by  a very  fine  mucous 
membrane  continuous  with  that  of  the  pharynx  and  of  the 
tympanum.  This  membrane  is  thickened  at  its  anterior  ex- 
tremity by  the  mucous  glands  beneath  it,  which  assist  in 
giving  the  marked  elevation  to  its  orifice.  The  canal  di- 
minishes as  it  goes  backwards,  so  as  to  receive  with  diffi- 
culty a- small  probe. 


THE  TVMBANUM. 


431 


Parallel  with  the  bony  part  of  this  canal,  but  above  it 
and  separated  by  a very  thin  partition  of  bone,  is  another 
■canal  which  lodges  a muscle  of  the  malleus.  On  the  outer 
side  of  the  eustachian  tube  is  the  glenoid  foramen,  by  which, 
in  the  dried  bone,  the  tympanum  communicates  with  the 
glenoid  cavity;  in  the  recent  state,  the  foramen  receives  the 
long  process  of  the  malleus  and  its  muscle,  and  transmits 
the  chorda  tympani. 

There  are  four  bones  in  the  tympanum,  which,  being  suc- 
cessively articulated  with  each  other,  form  a chain,  one  end 
of  which  is  fastened  to  the  membrana  tympani,  and  the 
other  end  rests  upon  the  foramen  ovale.  They  are  the 
Malleus;  the  Incus;  the  Orbiculare;  and  the  Stapes. 

The  Malleus  forms  the  fore  part  of  the  chain,  and  is 
placed  almost  vertically.  Its  superior  extremity  is  the  head, 
which  is  rounded,  with  the  exception  of  the  posterior  face, 
where  a small  concavo-convex  surface  is  observable,  for  the 
articulation  with  the  incus.  Its  lower  extremity  is  long 
and  tapering,  inclines  inwardly,  terminates  by  a little  knob, 
and  forms  an  angle  with  the  part  above;  this  portion  is  the 
manubrium,  and  adheres  its  whole  length  to  the  membrana 
tympani,  commencing  at  the  superior  margin  of  the  latter, 
and  insinuating  itself  between  the  internal  and  the  proper 
layer,  as  far  as  the  centre  of  the  membrane.  It  is  this  ad- 
hesion with  the  inclination  inwards  of  the  manubrium,  that 
causes  the  membrane  to  be  depressed  in  its  centre. 

Between  the  head  and  the  manubrium  is  a short  portion 
called  the  neck.  From  the  superior  external  extremity  of 
the  manubrium  there  proceeds  outwardly  the  short  process 
{Processus  Brevis;)  and  from  the  front  of  the  neck,  there 
proceeds  the  long  and  very  delicate  process,  concave  ex- 
ternally and  convex  internally,  which  is  insinuated  into 
the  glenoid  foramen,  and  is  the  Processus  Longus  or  Gra- 
cilis. 

The  Incus  is  behind  the  malleus,  and  is  also  upright.  It 
consists  in  a body  and  two  branches,  which  diverge  very 


432 


NKRVOUS  SYSTEM. 


considerably,  and  has  a general  resemblance  to  a molar 
tooth.  The  body  presents  on  its  fore  part  a deep  concavity, 
which  articulates  with  the  convex  head  of  the  malleus.  The 
branch  which  arises  from  the  back  part  of  the  body  is  ho- 
rizontal, looks  into  the  orifice  of  the  mastoid  cells,  and  is 
much  shorter  than  the  other.  The  inferior  branch  is  long, 
upright,  tapering,  and  nearly  parallel  with  the  manubrium 
of  the  malleus,  but  somewhat  within  it. 

The  Orhiculare  is  a very  small  flattened  sphere  of  bone, 
which  articulates  with  the  lower  end  of  the  long  process  of 
the  incus,  and  in  adult  life  is  most  generally  fused  into  it, 
so  as  to  lose  its  distinctive  character:  the  latter  change  some- 
times occurs  even  in  early  infancy. 

The  Stapes  is  the  last  of  the  chain.  It  resembles  very 
strongly  the  common  stirrup  iron,  from  whence  its  name, 
and  is  placed  horizontally  at  right  angles  to  the  incus,  being 
separated  from  the  extremity  of  the  long  process  of  the  lat- 
ter by  the  os  orbiculare,  and  being  directed  inwards  to  the 
foramen  ovale.  It  is  composed  of  a head,  two  crura,  and 
a base. 

The  head  is  oblong  and  flattened:  it  has  a slight  depres- 
sion where  it  joins  the  orbiculare.  The  crura  are  slightly 
curved,  with  the  concavities  towards  each  other;  the  ante- 
rior is  somewhat  straighter  than  the  posterior,  and  is  also 
shorter.  They  are  both  excavated  longitudinally  on  their 
concave  surfaces,  and  between  them  is  stretched  a process 
of  the  lining  membrane  of  the  tympanum.  The  base  is 
precisely  adapted  to  the  fenestra  ovalis,  and  is  connected  to 
it  by  the  lining  membrane  of  .the  tympanum,  but  not  so 
closely  as  to  prevent  it  from  executing  slight  vibratory 
movements. 

Between  the  malleus  and  the  incus  there  is  a moveable 
articulation  with  a synovial  membrane,  but  the  other  joints 
of  the  chain  are  simply  ligamentous. 

7’his  chain  of  bones  is  moved  by  several  muscles,  which 


THE  TYMPANUM. 


433 


thereby  influence  the  degree  of  tension  of  the  membrana 
tympani. 

1.  The  Laxator  Tympani  arises  from  the  posterior  end 
of  the  spinous  process  of  the  sphenoid  bone,  and  passing  be- 
hind the  articulation  of  the  lower  jaw  into  the  glenoid  fo- 
ramen, is  inserted  tendinous  along  the  processus  gracilis  of 
the  malleus. 

It  draws  the  malleus  forwards  and  outwards,  so  as  to  re- 
lax the  membrana  tympani. 

2.  The  Tensor  Tympani  is  placed  in  the  canal  just  above 
the  Eustachian  Tube.  It  arises  from  the  posterior  extre- 
mity of  the  cartilaginous  portion  of  the  latter,  and  having 
got  into  the  tympanum,  is  changed  into  a small  tendon, 
which,  going  outwardly,  is  inserted  into  the  neck  of  the 
malleus,  just  below  its  processus  gracilis. 

It  draws  the  malleus  inwardly,  consequently  makes  tense 
the  membrana  tympani,  and  drives  the  stapes  into  the  fenes- 
tra ovalis. 

,3.  The  Stapedius  arises  from  the  bottom  of  the  cavity  in 
the  pyramid,  and  terminates  in  a small  round  tendon,  which, 
going  through  the  apex  of  the  latter,  is  inserted  into  the  head 
of  the  stapes. 

It  d raws  the  stapes  backwards,  and  perhaps  fixes  it  more 
firmly  by  its  contractions. 

4.  There  is  a fourth  muscle  mentioned  by  anatomists, 
the  existence  of  which  is  more  equivocal;  it  is  called  the 
Laxator  Tympani  Minor.  It  arises  from  the  superior  mar- 
gin of  the  orifice  of  the  tympanum,  and  is  inserted  into  the 
processus  brevis  of  the  Malleus.  It  is  by  some  considered 
only  as  a ligament,  to  which  opinion  I am  inclined. 

Of  the  Lining  Membrane  of  the  Tympanum. 

This  membrane  is  a continuation  of  the  lining;  membrane 
of  the  pharynx,  being  introduced  into  the  tympanum  through 
VoL.  IL— -55 


-13-1 


NEKVOUS  SYSTEM. 


tlie  Eustachian  Tube.  It  covers  completely  the  surface  of 
the  tympanum,  and  is  reflected  over  its  little  bones  so  as  to 
give  them  a covering  also:  in  addition  to  which,  it  lines 
such  of  the  mastoid  cells  as  communicate  with  the  tym- 
panum. 

This  membrane  is  extremely  delicate;  on  its  surface,  adja- 
cent to  the  bones,  it  is  somewhat  fibrous,  and  thereby  resem- 
bles periosteum;  but  the  other  surface  has  the  characters  of 
the  mucous  membranes  generally,  in  the  nature  of  its  secre- 
tion, and  in  its  vascularity,  which  is  very  strongly  marked 
in  inflammations,  and  by  fine  injections.  Bichat  mentions, 
that  in  certain  catarrhal  affections  its  mucous  secretion  is 
so  abundant  as  to  fill  the  whole  cavity  of  the  tympanum, 
and  that  without  ulceration.  Sometimes  in  such  cases  the 
membrane  of  the  tympanum  is  ruptured,  and  the  discharge 
finds  its  way  out  through  the  meatus  externus,  presenting 
itself  under  a purulent  form,  as  if  an  abscess  had  formed  in 
tlie  ear. 


SECT.  III. — OF  THE  LABYRINTH.  '^ 

The  Labyrinth  (^Lahyrinthus)  is  placed  on  the  inner  side 
of  the  tympanum,  in  the  thickness  of  the  petrous  bone. 
Its  exterior  parietes  are  bone,  but  internally  there  is  a mem- 
branous structure,  having,  in  many  respects,  the  same  shape. 
It  is  got  at  with  great  difficulty  in  the  adult,  owing  to  the- 
compactness  of  the  petrous  bone  which  envelops  it,  but  in 
the  foetus  of  the  full  period,  where  it  is  almost  as  large  as 
in  the  adult,  the  surrounding  bone  is  of  a softer  and  more 
spongy  texture,  and  may  be  pared  away  with  a pen-knife 
without  much  trouble.  In  the  latter  case,  the  parietes  of 
the  bony  labyrinth  are  about  the  thickness  of  an  egg-shell, 
and  have  very  much  the  same  degree  of  consistency  and 
strength. 

The  bony  labyrinth  consists  of  three  portions:  the  Ves- 
tihulum,  the  Semicircular  Canals,  and  the  Cochlea. 

* Antonio  Scarpa,  Disquisit.  de  auditu  et  olfiicto, 


THE  LABYRI>CTH. 


435 


The  Vestihulum  is  the  cavity  to  which  the  foramen 
ovale  leads;  it,  with  the  cochlea,  occasions  the  protuberance 
into  the  tympanum,  known  as  the  promontory.  It  is  an 
h’regular  rounded  excavation,  the  surface  of  which  is  im- 
pressed by  its  contents;  thus,  at  its  superior,  posterior,  and 
external  part,  next  to  the  semicircular  canals,  there  is  a su- 
perficial Fossa,  called,  from  its  shape,  Senii-Elliptica,  and 
at  its  anterior  and  inferior  part,  nearer  the  cochlea,  another, 
called  Fossa  Hemi-spherica.  These  fossae  are  marked  oft' 
from  each  other  by  a ridge  of  bone,  at  the  lower  end  of 
which  there  is  third  fossa,  between  the  other  two,  called, 
by  Soemmering,  Cavitas  Sulciformis. 

There  are  seven  orifices  besides  the  foramen  ovale;  five 
at  its  posterior  part  leading  into  the  semicircular  canals;  one 
anteriorly  leading  into  the  upper  scala  of  the  cochlea:  and 
the  last  placed  in  its  internal  parietes  is  the  aqueduct  of  the 
vestibule.  In  addition  to  these  orifices,  the  parietes  of  this 
cavity  are  cribriform  in  the  fossa  semi-ellipticaand  near  the 
foramen  rotundum.* 

The  Semicircular  Canals  {Canales  Semicirculares)  are  at 
the  posterior  extremity  of  the  vestibulum.  They  are  three 
in  number,  and  are  named,  from  their  relative  situation, 
Superior  or  Anterior,  Posterior  or  Inferior,  and  External. 
Each  one  forms  rather  more  than  the  half  of  a semicircle, 
and  has  its  cavity  about  half  a line  in  diameter:  their  ori- 
fices are  somewhat  dilated  beyond  this  measurement.  The 
apparent  thickness  of  their  parietes  is  greater  in  the  adult 
than  in  the  infant. 

The  Superior  Canal  runs  from  without  inwards  and  back- 
wards. Its  anterior  orifice  is  above  the  fenestra  ovalis,  and 
is  enlarged  into  an  ampulla  or  elliptical  cavity.  At  its  pos- 
terior extremity,  it  joins  the  upper  extremity  of  the  inferior 
canal,  so  that  a common  trunk  is  thus  formed,  the  orifice  of 
which  is  at  the  internal  posterior  part  of  the  vestibulum, 
and  is  dilated  into  the  shape  of  a funnel,  t 

The  Posterior  or  Inferior  Canal  is  nearly  vertical;  has  its 


* Ant.  Scarpa,  loc.  cit. 


t Scarpa,  loc.  cIt. 


NERVOUS  SYSTEM. 


4o« 

concavity  in  front  and  its  convexity  beliind,  and  joins,  as 
just  remarked,  with  the  superior:  its  inferior  orifice,  which 
is  near  the  foramen  rotundum,  is  also  enlarged  into  an  am- 
pulla or  elliptical  cavity.  It  is  the  longest  of  the  three 
canals,  and  has  its  branches  nearer  together. 

The  External  Canal  is  nearly  horizontal,  and  is  placed 
in  the  space  left  by  the  divergence  of  the  other  two.  It  is 
the  shortest  and  the  largest  of  the  three.  Its  exterior  orifice 
is  also  enlarged  into  an  ampulla  or  elliptical  cavity,  and  is 
just  behind  the  foramen  ovale,  or  below  the  ampulla  of  the 
upper  canal;  the  internal  orifice  is  below  the  common  open- 
ing Sf  the  other  two  canals. 

It  is  the  union  of  the  superior  and  of  the  posterior  canals 
at  one  of  their  extremities,  which  reduces  the  number  of  ' 
openings  into  the  vestibulum,  from  the  semicircular  canals, 
to  five  instead  of  six. 

I The  Cochlea  forms  the  fore  part  of  the  labyrinth,  and  re- 
sembles very  strongly  the  shell  of  the  common  snail.  Its 
base  is  the  bottom  of  the  meatus  auditorius  internus,  and  its 
apex  is  directed  towards  the  cavity  of  the  tympanum,  so  that 
the  axis  of  the  cochlea  is  turned  downwards  and  outwards. 
It  consists  in  a conoidal  tube  wound  spirally  t'’  ice  and  a half 
around  a column  of  bone  termed  the  Modiolus.  'I'he  tube 
then  of  course,  diminishes  in  size  from  the  base  to  the  apex 
of  the  cochlea. 

This  conical  tube  is  divided  in  its  length  by  a plate  called 
Lamina  Spiralis.  Of  the  two  compartments  thus  formed,  , 
one  is  above  the  other.  The  inferior  is  the  larger,  and  com- 
municates at  its  base,  through  the  foramen  rotundum,  with 
the  tympanum;  it  is  therefore  called  Scala  Tympani.  The 
other  compartment  communicates  at  its  base  with  the  ves- 
tibulum, and  is  therefore  called  Scala  Vestibuli, 

The  Modiolus  is  of  a conical  shape  and  cribriform:  one 
canal,  larger  than  the  others,  runs  from  its  base  to  its  sum- 
mit. This  canal  is  surrounded  by  many  others,  which  dimi- 
nish successively  as  they  advance  towards  the  apex  and 
terminate  in  orifices  upon  the  lamina  spiralis.  This  cribri 


'i’Hi;  LABYKINTH. 


'iJT 

form  arrangement  of  the  modiolus  is  the  Tractus  Spiralis 
Foraminulosus.  The  base  of  the  modiolus?  is  towards  the 
meatus  auditorius  internus,  and  its  point  does  not  go  to  the 
apex  of  the  cochlea  but  stops  short  of  it,  and  is  expanded 
into  a cavity  called  the  Infundibulum,  the  base  of  which  is 
towards  the  apex  of  the  cochlea.  That  portion  of  the  apex 
of  the  cochlea  which  covers  over  the  infundibulum  is  the 
Cupola. 

It  was  just  mentioned  that  the  lamina  spiralis  divides  the 
cochlea  into  two  tubes;  the  septum  thus  formed,  does  not 
however  run  their  whole  length,  for  it  ceases  in  the  infun- 
dibulum by  a small  crooked  process  of  bone,  called  the  Ha- 
mulus Cochleae.  The  lamina,  when  examined  by  strong 
glasses,  is  seen  to  consist  of  four  distinct  structures  called 
its  Zones.  1.  The  Zona  Ossea  is  next  to  the  modiolus,  and 
is  composed  of  two  bony  laminae,  with  an  intermediate 
diploic  structure,  in  which  are  the  canals  for  transmitting 
the  filaments  of  the  portio  mollis  or  auditory  nerve.  2.  The 
Zona  Coriacea,  on  the  outer  side  of  this,  the  structure  of 
which  is  cartilaginous.  3.  The  Zona  Vesicularis,  said  to 
contain  in  its  cells  a pellucid  fluid.  4.  The  Zona  Meni- 
branacea,  which  is  probably  only  the  lining  membrane  of 
the  cochlea,  and  completes  the  lamina  spiralis  on  its  edge 
next  to  the  periphery  of  the  cochlea.  Some  very  respectable 
anatomists  pass  over  this  minute  distinction  in  the  structure 
of  the  septum,  and  merely  divide  it  into  Zona  Ossea,  and 
into  Zona  Mollis. 


0/'  the  Membranous  Labyrinth. 

The  whole  internal  face  of  the  bony  Labyrinth  is  lined 
by  a very  delicate  and  vascular  membrane,  which  is  more 
distinct  during  the  early  periods  of  intra-uteri ne  life.  Be- 
sides this,  there  is  a membranous  labyrinth,  consisting  in 
three  semicircular  canals,  nearly  filling  up  the  cavities,  and 
having  the  same  shape  and  general  arrangement  of  the  hony 
canals;  and  in  two  sacs  contained  in  the  vestibule. 


438 


^’ERVOUS  SYSTEM. 


The  Semicircular  Membranous  Canals  have  also  at  their 
ends  the  elliptical  enlargements  called  ampullae;  they  ter- 
minate by  both  extremities  in  the  sac  of  th^  superior  part 
of  the  vestibule.  This  sac  is  generally  called,  from  its  shape, 
Sacculus  Ellipticus;  and  by  Scarpa,  from  its  function,  the 
Alveus  Communis.  In  front  of  the  Sacculus  Ellipticus, 
nearer  the  cochlea,  and  opposite  the  foramen  ovale,  is  the 
Sacculus  Sphericus;  it  is  a complete  bag,  having  no  commu- 
nication with  the  other,  or  with  the  membranous  canals. 
Both  of  the  sacs  adhere  to  the  vestibulum  at  their  posterior 
parietes. 

The  sacs  of  the  vestibule  and  the  membranous  semicir- 
cular canals  are  filled  with  a very  fluid  transparent  liquid. 
According  to  the  observations  of  M.  Ribes,  it  is  not  neces- 
sary to  the  function  of  hearing  that  this  fluid  shouW  be  so 
abundant  as  to  distend  tbe  membranous  labyrinth,  inasmuch 
as  in  his  dissections  he  met  with  individuals  in  whom  the 
latter  was  only  half  filled,  and  yet  they  had  heard  very  well. 
He  also  met  with  similar  cases  in  which  the  fluid  was  abun- 
dant in  the  vestibulum,  but  deficient  in  the  canals,  and  the 
reverse.  Corresponding  observations  have  been  made  by 
M.  Brugnone,  of  Turin,*  where  he  had  adopted  the  precau- 
tion of  previously  freezing  the  bone,  so  that  none  of  the 
fluid  could  be  said  to  have  been  lost  by  accident.  From  the 
frequency  with  which  this  deficiency  was  observed,  his 
opinion  seems  to  be  well  founded,  that  it  is  the  most  natural 
state  of  the  labyrinth. 

The  parietes  of  the  membranous  labyrinth  are  very  thin 
and  transparent;  there  is  a very  loose  cellular  tissue  between 
them  and  the  bone,  and  they  are  susceptible  of  being  highly 
coloured  by  injection. 

A fluid  of 'the  same  character  with  the  preceding  also 
fills  the  scalse  of  the  cochlea,  and  extends  itself  into  the  bony 
vestibulum  and  the  bony  semicircular  canals  upon  the  outer 
surface  of  the  membranous  labyrinth. 

.Mem.  de  Turin,  1805 — 1808. 


THE  XABYRINTH. 


Of  the  Aqueducts  of  the  Ear. 

The  Aqueducts  {Aquseductus')  of  Cotunnius,  as  they  are 
called,  are  two  small  canals  which  go  through  the  petrous 
bone  from  the  labyrinth.  There  is  one  for  the  vestibule,  and 
another  for  the  cochlea. 

The  Aqueduct  of  the  Vestibulum,  commences  in  the  lat- 
ter cavity,  somewhat  in  advance  of  the  common  orifice  of 
the  two  semicircular  canals;  it  goes  inwards,  and  opens  on 
the  posterior  face  of  the  petrous  bone,  behind  the  meatus 
internus.  It  enlarges  gradually  in  its  course,  which  causes 
it  to  have  somewhat  of  a triangular  shape,  and  it  is  lined 
by  a continuation  of  the  dura  mater.  It  is  about  four  lines 
long. 

The  Aqueduct  of  the  Cochlea  commences  in  the  Scala 
Tympani,  near  the  foi’amen  rotundum  and  enlarging  in  its 
course  terminates  on  the  under  surface  of  the  petrous  bone, 
in  the  internal  margin  of  the  jugular  fossa,  at  the  root  of 
the  little  spine  which  separates  the  eighth  pair  of  nerves 
from  the  jugular  vein. 

The  anatomist*  from  whom  these  canals  were  named,  and 
who  first  described  them,  was  under  an  impression  that  the 
fluid  of  the  labyrinth  always  filled  it  completely,  and  that 
without  a sort  of  waste  gate  for  it  on  an  occasion,  the  vibration 
of  the  stapes  would  be  prevented  fronr  putting  it  in  motion, 
consequently  hearing  must  cease.  These  canals,  the  exist- 
ence of  which  is  sufficiently  obvious  in  many  subjects,  were, 
therefore,  considered  by  him  as  the  desired  avenues  for  the 
discharge  of  the  superabundant  fluid,  and  his  theory  and 
descriptions  were  very  generally  adopted.  Of  late  years 
the  investigation  of  this  subject  has  been  renewed  by  MM. 
Ribes  and  Brugnone,  and  their  observations  are  considered 
by  the  French  anatomists,  to  have  proved  conclusively,  the 
error  into  which  Cotunnius  and  others,  have  fallen. 

In  regard  to  the  aqueduct  of  the  vestibule,  M.  Ribes  has 
found  it  only  in  three  instances  emptying  into  the  vestibule; 


Dominici  Cotunnii,  Anat.  Dissert,  de  Aquaeduct.  Naples,  1761. 


140 


NEKVOUS  SYSTEM. 


for  most  commonly  it  leads,  after  a course  somewhat  tor- 
tuous, into  the  spongy  structure  of  the  petrous  bone,  at  the 
posterior  part  of  the  vestibule,  and  smaller  canals  diverge 
from  it  in  difierent  directions.  In  the  cases  where  it  was 
connected  with  the  labyrinth,  it  was  so  by  several  orifices 
leading  into  the  vestibule,  and  into  the  posterior  semicircu- 
lar canal.  He  has  not  found  this  canal  in  the  fcstus  or  till 
some  time  after  birth,  and  from  his  injections  he  believes 
that  in  all  cases  it  and  its  branches  are  only  intended  to 
convey  blood  vessels  throughout  the  petrous  bone  and  to 
the  labyrinth. 

In  regard  to  the  supposed  aqueduct  of  the  cochlea,  M. 
Ribes  has  also  found  it  diverging  into  collateral  branches, 
and  occupied  by  blood  vessels,  which  are  distributed  to  the 
spongy  structure  of  the  petrous  bone,  and  to  the  tympanum. 

In  my  own  researches  on  this  point,  on  the  dried  bones, 
the  canals,  as  described  by  Cotunnius,  were  closed  at  the 
lahyrinth  in  the  case  of  subjects  advanced  in  life;  but  in  the 
middle  aged  and  in  infantile  specimens,  I have  been  more 
successful  in  tracing  them  fairly  into  the  labyrinth,  and 
have  the  preparations  in  the  Wistar  Museum.  At  the  same 
time  I think  it  much  more  probable  that  they  only  contained 
blood  vessels,  and  that  Cotunnius  was  in  error.  Besides 
these  vascular  canals,  M.  Ribes  has  described  some  others 
having  the  same  use. 

SECT.  IV. OE  THE  NERVES  OE  THE  ORG-AN  OE  HEARING. 

The  Nerves  which  pass  through  the  petrous  bone,  and 
are  either  wholly  or  partially  spent  upon  the  organ  of  hear- 
ing come  from  three  sources.  1.  The  Auditory.  Nerve;  2. 
The  Portio  Dura;  3.  The  Trigeminus  or  Fifth  Pair. 

The  Meatus  Auditorius  Internus  conducts  the  two  first  and 
has  its  bottom  divided  by  a ridge  into  two  fossae,  of  which 
the  upper  one  is  the  smaller.  This  bottom,  it  has  been  ob- 
served, corresponds  with  the  base  of  the  modiolus,  and  is 
cribriform.  One  foramen  larger  than  any  of  the  others,  and 
in  the  superior  fossa,  transmits  the  portio  dura  or  facial 


NERVES  OP  THE  ORGAN  OP  HEARING. 


441 


nerve,  all  the  others  are  occupied  by  the  filaments  of  the 
auditory  nerve. 

1.  The  Auditory  Nerve  divides  at  the  bottom  of  the  mea- 
tus into  fasciculi  of  filaments;  one  of  which  penetrates  into 
the  vestibulum  through  the  foramina  behind  that  for  the  por- 
tio  dura,  and  is  distributed  upon  the  sacculus  ellipticus,  and 
upon  the  ampulla  of  the  superior  and  of  the  exterior  mem- 
branous canal;  other  filaments  get  to  the  sacculus  sphericus; 
and  a third  fasciculus  of  filaments  is  distributed  to  the  am- 
pulla of  the  posterior  membranous  canal.  These  several 
filaments  are  said  to  preserve,  when  they  first  penetrate  into 
the  bony  labyrinth,  a fibrous  appearance,  and  are  interlaced; 
they  also  penetrate  the  parietes  of  the  membranous  lab)'- 
rinth  and  have  their  extremities  bathed  in  its  fluid,  in  which 
place  they  are  converted  into  a soft  pulp,  resembling  m.ucus 
or  the  retina. 

Another  very  considerable  fasciculus  of  filaments  pene- 
trates into  the  canals  of  the  modiolus,  and  enters  through 
them  into  the  cavity  of  the  cochlea,  along  the  Zona  Ossea, 
and  between  its  tables;  they  terminate  also  by  a soft  pulp 
on  the  internal  face  of  the  lining  membrane  of  the  cochlea. 
One  of  these  filaments,  conspicuous  for  its  size,  goes  through 
the  central  canal  of  the  modiolus  and  terminates  in  the  in- 
fundibulum.* 

2.  The  Facial  Nerve  is  only  connected  to  the  organ  of 
hearing  by  sending  a few  filaments  to  the  muscles  of  the 
bones  of  the  tympanum.  The  canal  of  the  petrous  bone, 
through  which  it  passes,  is  very  crooked;  beginning  at  the 
larger  orifice  of  the  meatus  internus  in  its  upper  fossa,  it 
passes  outwards  until  it  nearly  reaches  the  vidian  foramen, 
on  the  front  of  the  petrous  bone;  it  then  turns  very  abrupt- 
ly backwards,  forming  an  angle,  and  is  continued  in  a cir- 
cuit around  the  superior  and  the  posterior  parietes  of  the 

* For  a knowledge  of  the  minute  distribution  of  the  auditor)^  nerve,  the 
profession  is  signally  indebted  to  the  distinguished  Scarpa,  in  liis  Disquisi- 
tiones  de  Auditu  at  Olfactu. 

Voi.  II. — 56 


-142 


NEllVOUS  SYSTEM- 


tympanum,  till  it  terminates  in  the  stylo-mastoid  foramenv 
Its  course  is  marked  by  a ridge  projecting  into  the  tympa- 
num, above  the  foramen  ovale,  and  passing  between  the  se- 
micircular canals  and  the  cochlea.  This  canal  has  been  very 
much  misnamed  by  the  calling,  of  it  the  aqueduct  of  Fallo- 
pius, as  its  only  use  is  to  conduct  nerves  and  blood  vessels. 
It  is  lined  by  a delicate  fibrous  membrane,  between  which 
and  its  contained  parts  there  is  so  little  adhesion,  that  the 
latter  may  be  drawn  out  entire. 

The  facial  nerve  is  joined  at  the  vidian  foramen  by  the 
vidian  nerve,  shortly  after  which  it  sends  a filament  to  the 
tensor  tympani  muscle.  As  it  passes  the  base  of  the  pyra- 
mid it  detaches  another  filament,  which  supplies  the  stape- 
dius muscle.  Shortly  after  this  it  is  abandoned  by  the  vi- 
dian nerve,  and  does  not  give  off  any  more  branches  till  it 
escapes  from  the  stylo-mastoid  foramen,  when  it  sends  off 
a branch,  the  posterior  auricular,  [Auricularis  Posterior,) 
which  is  distributed  by  filaments,  some  of  which  run  into 
the  mastoid  process;  others  mounting  on  the  side  of  this  pro- 
cess, go  to  the  skin  which  covers  it,  and  to  the  occipital 
muscle;  others  go  to  the  concha  of  the  ear,  being  spent  upon 
its  skin,  upon  the  posterior  auricular  muscle,  and  some  of 
them,  penetrating  the  pinna,  are  lost  upon  the  integuments 
of  the  meatus  externus. 

3.  The  Chorda  Tympani  or  Superficial  Petrous  Nerve, 
is  a branch  of  the  Pterygoid  branch  of  the  Trigeminus,  and 
leaves  it  near  the  anterior  part  of  the  carotid  canal  of  the 
petrous  bone.  It,  as  just  mentioned  under  the  name  of  vi- 
dian nerve,  joins  the  facial  nerve  at  the  angle  of  the  canal 
of  Fallopius,  and  continues  to  adhere  closely  to  it,  almost 
to  the  styloid  foramen;  it  then  abandons  the  facial  nerve  at  a 
very  acute  angle,  and  running  upwards  and  forwards,  gets 
into  the  cavity  of  the  tympanum,  on  a level  with,  but  a line 
or  two  exterior  to  the  pyramid.  It  then  crosses  the  tympa- 
num nearly  horizontally,  between  the  long  crus  of  the  incus 
and  the  handle  of  the  malleus,  adhering  to  the  latter  so  as  to 
be  affected  by  its  vibrations.  At  the  fore  part  of  the  tympa- 


NERVES  OP  THE  ORGAN  OF  HEARING. 


443 


num  it  anastomoses  with  some  other  filaments  of  the  fifth 
pair,  by  which  its  size  is  augmented,  but  it  gives  no  bran- 
ches to  the  parts  contained  in  the  tympanum.  It  then  is- 
sues from  the  latter  cavity  through  the  glenoid  foramen, 
and  descending  a short  but  somewhat  variable  distance  along 
the  ramus  of  the  lower  jaw,  terminates  by  anastomosing  at 
an  acute  angle  with  the  lingual  branch  of  the  trigeminus. 

To  Mr.  John  Hunter  is  due  the  merit  of  having  traced 
the  continuity  and  identity  of  the  vidian  nerve  with  the 
chorda  tympani.  The  continental  anatomists,  fOr  the  most 
part,  seem  ignorant  of  his  observations,  and  give  a very  dif- 
ferent account  of  the  matter.  Some  call  the  vidian  nerve  the 
superficial  petrous,  consider  it  to  arise  from  the  facial,  and 
to  anastomose  at  the  other  end  with  the  pterygoid,  or  the 
reverse;  and  they  very  generally  agree  in  regarding  the 
chorda  tympani  as  a filament  from  the  facial,  just  before  the 
latter  gets  out  of  the  stylo-mastoid  foramen. 

The  Vidian  Nerve  or  Superficial  Petrous  also  traverses 
the  tympanum  in  another  place.  Just  below  the  posterior 
extremity  of  the  Eustachian  Canal,  there  is  a small  foramen, 
which  leads  upwards  to  the  superior  surface  of  the  petrous 
bone,  and  downwards  to  a small  gutter  upon  the  promontory; 
this  gutter  is  converted  into  a canal  that  opens  upon  the 
under  surface  of  the  petrous  bone,  between  the  carotid  canal 
and  the  jugular  fossa.  Through  the  course  indicated  passes 
a filament  from  the  superficial  petrous  nerve;  this  filament 
is  joined  by  another  detached  from  the  sympathetic  while 
in  the  carotid  canal,  and  the  two  communicate  at  the  base 
of  the  cranium  with  the  ganglion  of  the  glosso-pharyngeal 
nerve.*  These  filaments  were  discovered  by  Professor  Ja- 
cobson of  Copenhagen. 

* Meckel,  Man.  D’Anat.  vol.  iii.  p.  174.  Jacobson,  Supplementa  atl 
otoia  triam,  Act.  Hafn.  vol,  v.  p.  292.  An.  1818. 


■144 


>'ERVOUS  SYSTEM. 


CHAPTER  III. 

OF  THE  ORGAN  OF  SMELLING,  OR  THE  NOSE. 

The  two  preceding  senses  are  so  insulated  in  their  offices, 
that  there  can  be  no  doubt  of  the  propriety  of  considering 
them  as  belonging  to  the  peripheral  portion  of  the  nervous 
system.  But  the  nose  being,  in  the  human  subject,  though 
not  in  all  animals,  associated  with  the  function  of  respira- 
tion, its  collocation  is  less  exceptionable.  Without  detailing 
the  considerations  which  have  induced  me  to  put  its  de- 
scription under  this  head,  I will  only  mention  that  I have 
been  principally  actuated  by  its  office  of  smelling  and  by 
its  position. 

In  common  language,  the  term  nose  is  applied  to  the  part 
of  the  organ  of  smelling  which  manifests  itself  externally; 
but  a very  extensive  cavity  of  the  same  vertical  diameter, 
and  divided  into  two  equal  compartments,  exists  behind  it. 
This  cavity  extends  from  the  basis  of  the  cranium  to  the 
roof  of  the  mouth,  and  backwards  to  within  an  inch  and  a 
quarter  of  the  vertebrae  of  the  neck.  The  nose,  externally, 
is  generally  pyramidal,  and  has  its  base  below;  what  is  tech- 
nically called  the  root  of  the  nose  is  the  part  contiguous  to 
the  forehead.  The  base,  on  each  side,  is  marked,  from  the 
cheek,  by  a semicircular  depression;  which  becoming  more 
and  more  shallow  at  its  upper  extremity,  and  increasing  its 
breadth,  is  insensibly  lost  upon  the  side  and  point  of  the 
nose.  The  ala  nasi  is  the  swell  of  the  posterior  part  of  the 
base,  being  bounded  behind  by  the  depression.  The  base  of 
the  nose  offers,  on  each  side,  an  oblong  oval  orifice  looking 
downwards,  and  having  its  long  diameter  forwards  and 
slightly  inwards.  These  openings  are  commonly  about  two 
lines  below  the  floor  of  the  nose,  but  there  is  a diversity  in 
this  respect. 

The  Nasus  Cartilagineus,  or  the  cartilaginous  portion  of 
the  nose,  is  placed  wholly  at  its  anterior  extremity,  and 


ORGAN  OF  SMELLING. 


445 


sei'ves  to  elongate  the  cavity  in  that  direction.  It  presents 
a vertical  cartilage,  which  is  a continuation  of  the  bony  sep- 
tum; on  each- side  of  this,  there  is  an  oval  cartilage,  and 
behind  and  below  the  latter,  several  distinct  and  small 
pieces  of  cartilage,  which  preserve  the.  form  of  the  alas  nasi, 
and,  in  fact,  constitute  them. 

The  Cartilaginous  Septum  {Septum  Cartilagineum)  is 
placed  precisely  in  the  middle  line  of  the  nose,  and  has  its 
anterior  angle  projecting  beyond  the  bony  orifice  of  the  an- 
terior naris.  Occasionally,  from  a faulty  conformation,  it 
inclines  more  to  one  side  than  to  the  other.  It  adheres,  by 
its  superior  margin,  to  the  nasal  lamella  of  the  ethmoid  and 
the  middle  nasal  suture,  and  behind  to  the  anterior  margin 
of  the  vomer.  The  inferior  margin  is  free  in  the  greater 
part  of  its  extent,  but  adheres  behind  to  the  suture  between 
the  maxillary  bones.  The  anterior  margin  sends  out,  on 
either  side,  a triangular  plate,  the  upper  edge  of  which  ad- 
heres to  the  inferior  margin  of  the  nasal  bone,  and  of  the 
nasal  process  of  the  upper  maxillary.  These  plates  form  the 
upper  part  of  the  cartilaginous  nose,  and,  from  their  liga- 
mentous attachment  to  the  bones,  admit  of  a slight  motion 
from  side  to  side. 

The  Oval  Cartilages,  one  on  each  side,  are  a spdcies  of 
elliptical  ring,  but  deficient  or  open  at  their  posterior  end. 
The  external  side  of  the  ring  is  an  oblong  oval  plate,  which 
is  directed  upwards  and  backwards.  The  internal  half  of 
the  ring  is  much  narrower,  and  proceeds  backwards  from 
the  preceding  part  at  a very  acute  angle;  its  superior  mar- 
gin is  in  contact  with  the  septum,  its  inferior  margin  reaches 
below  the  latter,  and  its  anterior  extremity  is  in  contact 
with  its  fellow,  owing  to  the  cartilaginous  septum  not  reach- 
ing so  far  forwards.  The  place  of  contact  of  the  two  oval 
cartilages  to  each  other,  forms  the  tip  of  the  nose  and  the 
columna  nasi,  and  gives  the  apparent  thickness  to  the  lower 
part  of  the  septum  narium  before  dissection. 

The  Alas  Nasi,  or  the  convexities  on  each  side  of  the  base 
of  the  nose,  it  has  been  said,  owe  their  shape  to  the  pre- 


NERVOUS  SYSTEM. 


44  G 

sence  of  several  small  pieces  of  cartilage.  Their  form,  size, 
and  number  are. too  variable  to  admit  of  a standard  descrip- 
tion; occ^^nally,  they  are  all  collected  into  but  one  carti- 
lage. They'sefve  a similar  purpose  with  the  oval  cartilage, 
and  with  it  are  the  means  by  which  the  orifice  of  the  nose 
is  kept  patulous.  They  are  deposited  in,  and  held  together 
by  a ligamentous  membrane.  This  membrane  attaches  them 
to  the  lateral  margin  of  the  anterior  bony  naris,  and  also 
unites  the  upper  edge  of  the  external  plate  of  the  oval  car- 
tilage to  the  inferior  margin  of  the  triangular  plate  of  the 
cartiiaginous  septum.  It  is  the  length  and  looseness  of  this 
ligament  which  permits  such  free  motion  to  the  end  of  the 
nose.  In  addition  there  exists  a small  ligament  described 
by  Caldani,  which  goes  from  the  posterior  end  of  the  co- 
lumna  nasi  to  the  anterior  inferior  margin  of  the  bony  naris. 

The  skin  which  covers  the  upper  half  of  the  nose  is  loosely 
attached,  by  cellular  substance,  to  the  subjacent  parts,  but 
it  adheres  very  closely'to  the  surface  of  the  cartilaginous 
and  ligamentous  structure,  and  is  abundantly  furnished  with 
sebaceous  glands  and  follicles.  The  exterior  orifices  of  the 
latter  are  apparent,  and  are  often  filled  with  their  appropri- 
ate fluid  in  an  inspissated  state,  which,  when  forced  out  by 
pressure,  assumes  the  form  of  small  worms,  the  blackness 
of  the  end  of  which  is  only  dirt. 

There  are  several  muscles  destined  to  move  the  cartila- 
ginous structure  of  the  nose,  which  have  been  described 
among  those  belonging  to  the  face. 

The  Levator  Labii  Superioris  Alaeque  Nasi,  which  lies 
upon  the  side  of  the  nose  and  comes  from  the  superior  part 
of  the  nasal  process  of  the  upper  maxillary  bone,  is,  besides 
its  insertion  into  the  upper  lip,  connected  with  the  ala  nasi, 
and  will  draw  the  latter  upwards. 

The  Compressor  Naris,  arising  from  the  ala  nasi  by  a 
small  pointed  beginning,  is  spread  out  upon  the  oval  carti- 
lage so  as  to  cover  it,  and  is  inserted  into  its  fellow  on  the 
middle  line. 

The  Depressor  Labii  Superioris  Alaeque  Nasi,  by  arising 


ORGAN  OF  S3IELI.ING. 


447 


from  the  roots  of  the  alveolar  processes  of  the  incisor  and 
canine  teeth  of  the  upper  jaw,  and  going  to  be  inserted  into 
the  ala  nasi,  as  well  as  into  the  upper  lip,  will  draw  the  ala 
nasi  downwards. 

The  Nasalis  Labii  Superioris,  or  Depressor  Narium, 
which  is  the  pointed  production  from  the  orbicularis.oris,  go- 
ing into  the  columna  nasi,  will  draw  the  latter  downwards 
and  backwards. 

The  Mucous  Membrane  of  the  Nose  {Membrana  Pitui- 
taria,  Schneideriana)  lines  the  whole  cavity  of  each  side 
of  the  nose,  penetrates  into  the  several  sinuses  and  cavities 
communicating  with  it,  and  is  continuous,  at  the  orifice  of 
the  nostrils,  with  the  skin,  and  at  the  posterior  nares,  with 
the  mucous  membrane  of  the  pharynx. 

It  is  not  of  essential  importance  to  begin  to  trace  its 
course  from  any  particular  point,'  but,  for  the  sake  of  per- 
spicuity, we  assume  the  floor  of  the  nostril,  which  it  covers 
in  a smooth  even  manner.  From  this  it  ascends  on  the 
septum  narium,  which  it  covers  also  smoothly  without 
forming  any  fold  or  duplicature,  and  adheres  so  loosely  that 
it  may  be  detached  with  great  facility.  Behind,  it  covers 
the  body  of  the  sphenoid  bone,  and  lines  its  cells;  in  front, 
it  covers  smoothly  the  ossa  nasi  and  nasal  processes  of  the 
upper  maxillary  bones,  and  also  the  cartilaginous  nose. 
Above,  it  is  reflected  upon  the  cribriform  plate  of  the  eth- 
moid bone,  and  blocks  up  all  its  foramina.  At  this  point, 
the  olfactory  nerves  seem  to  terminate  on  its  surface  and 
adhere  very  closely  to  it. 

From  the  cribriform  plate,  the  Schneiderian  membrane 
passes  to  the  cellular  part  of  the  ethmoid,  and  covers 
smoothly  its  anterior  half.  But  behind,  as  it  passes  over 
the  upper  spongy  bone,  a pendulous  duplicature  is  formed 
along  its  inferior  margin;  and  is  continued  beyond  the  bone, 
backwards  as  far  as  the  spheno  palatine  foramen.  It  then 
lines  the  upper  meatus  and  the  posterior  cells  of  the  eth- 
moid, and  is  extended  upon  the  convex  surface  of  the  mid- 
dle spongy  bone.  At  the  inferior  margin  of  the  latter,  it 


448 


NERVOUS  SYSTEM. 


forms  another  loose  and  somewhat  jjendulous  duplication, 
which  does  not  go  beyond  the  posterior  extremity  of  the 
bone.  The  membrane  is  then  reflected  into  the  middle 
meatus  of  the  nose,  and  penetrates  into  the  maxillary  sinus 
which  it  lines  completely.  The  orifice  through  which  it 
enters,  is  about  the  size  of  a crow-quill;  is  variable  in  its  si- 
tuation, being  sometimes  in  the  middle  of  the  meatus, 
sometimes  more  forward,  and  on  other  occasions  higher  up 
and  concealed  by  irregularities,  in  the  conformation  of  the 
ethmoid.  This  oriflce,  which  was  found  to  be  so  large  and 
jagged  in  the  dried  bone,  is  reduced  to  its  present  size  en- 
tirely by  the  mode  of  reflection  of  the  mucous  membrane 
over  its  margins.  In  front  of  the  latter  orifice,  beneath  the 
anterior  margin  of  the  middle  turbinated  bone,  the  mucous 
membrane  is  reflected  into  the  anterior  ethmoidal  cells  by 
one  or  more  foramina,  and  through  the  most  anterior  of 
these  cells  into  the  frontal  sinus. 

From  the  middle  meatus,  this  membrane  passes  upon  the 
lower  turbinated  bone  so  as  to  cover  it,  and  also  to  form  a 
loose  duplication  along  its  inferior  margin;  it  then  lines  the 
inferior  meatus  of  the  nose,  and  is  continued  on  its  floor 
into  the  part  from  which  its  description  commenced.  Un- 
der the  anterior  part  of  the  inferior  spongy  bone,  this  mem- 
brane is  continued  into  the  lining  membrane  of  the  lachry- 
mal sac,  and  there  forms  a fold,  frequently  resembling  a 
valve.  Along  the  posterior  margin  of  the  vomer,  the 
membranes  of  the  two  nostrils  are  continuous. 

The  pituitary  membrane,  in  its  structure  and  appearance, 
resembles  other  mucous  membranes;  its  colour,  however,  is 
naturally  of  a deeper  red.  It  consists  of  two  laminae,  which 
cannot  be  readily  separated;  the  one  next  to  the  cavity  of 
the  nostril  has  the  mucous  structure,  the  exterior  one  is 
fibrous,  and  resembles  the  periosteum  of  other  parts  of  the 
body.  This  composition  is  best  seen  on  the  part  belonging 
to  the  septum  narium. 

By  floating  the  pituitary  membrane  in  water  its  mucous 
lamina  is  made  to  exhibit,  very  satisfactorily,  the  villous 
and  spongy  appearance.  This  is  particularly  evident  on 


ORGAN  OF  SMELLING. 


449 


the  turbinated  bones.  Its  whole  surface  is  studded  with 
pits  or  follicles  of  various  sizes,  irregularl}''  arranged,  and 
resembling  pricks  made  into  a plastic  substance  with  the 
point  of  a pin.  From  these  cavities  or  cryptas  proceed  the 
mucus  of  the  nose.  In  the  thickness  of  the  pituitary  mem- 
brane, there  exist  numerous  and  thickly  set  glands,  of  a 
size  so  small  that  they  escape  common  observation,  but 
their  existence  is  generally  admitted,  both  on  the  authority 
of  anatomists  who  have  described  them,^  and  on  the  prin- 
ciple of  their  being  always  the  concomitants  of  mucous 
membranes,  t 

It  is  owing  to  the  great  abundance  of  blood  vessels  in  this 
membrane,  to  their  very  superficial  course,  and  to  the  ha- 
bitual residence  of  blood  in  them,  that  it  always  presents 
a deep  red  colour  in  the  living  state.  These  blood  ves- 
sels bleed  very  freely  from  slight  mechanical  causes,  and 
are  also  disposed  to  congestions,  which  are  relieved  by  the 
blood  being  poured  out  through  their  exhalent  orifices, 
without  laceration  or  any  solution  of  continuity. 

Though  the  description  just  given  corresponds  with  the 
texture  generally  of  the  pituitary  membrane,  yet  there  arc 
modifications  of  the  latter  at  particular  points  which  it  does 
not  fully  suit.  For  example;  at  the  anterior  orifice  of  the 
nostril  it  is  insensibly  changed  into  a thin  skin,  furnished 
in  the  male  adult  with  stiff  hairs  ( Vibrissse;)  and  in  all  the 
sinuses  it  is  more  thin  and  white  than  elsewhere,  being  also 
smooth  and  shining,  and  not  presenting  clearly  the  little 
pits  which  are  so  distinct  in  the  nose.  The  surface  which 
adheres  to  the  sides  of  the  sinuses,  is  destitute  of  a fibrous 
structure,  and  is  so  loosely  attached  that  it  peels  off  with  a 
very  inconsiderable  force.  When  the  membrane  of  the  si- 
nuses is  inflamed,  it  then  thickens,  admits  more  red  blood, 
and  is  thus  brought  to  resemble  the  pituitary  elsewhere. 

It  is  extremely  difficult  to  assign  a proper  .use  to  the  si- 
nuses entering  into  the  nose,  for,  according  to  Dessault,  the 
sensation  of  smell  does  not  exist  in  them.  Bichat  believed 

* Ruyschii,  Epist.  Anat.  Probl.  vii.  Mayer, 
f Bichat,  Anat.  Descrip. 

Vox.  II.— 57 


150 


KERVOUS  Sl'STEM. 


that  they,  by  being  filled  with  air  charged  with  odorous 
particles,  were  reservoirs  of  the  latter,  serving  to  prolong 
the  sensation  of  smell,  which  would  have  been  too  fugitive 
if  it  had  depended  only  on  the  passage  of  air  during  respi- 
ration. Another  problem  in  regard  to  these  cavities,  is  the 
manner  in  which  they  discharge  the  mucus  which  they  se- 
crete. Perfectly  rigid  and  unyielding,  and  so  situated  that 
the  most  frequent  attitudes  of  the  head  would  rather  serve 
to  retain,  than  to  discharge  the  contents  of  most  of  them 
by  gravitation,  we  yet  seldom  see  more  than  their  surface 
smeared  with  mucus,  and  accumulations  of  it  are  quite  un- 
common, except  in  the  diseased  state.  This  secretion  in 
them,  it  is  to  be  observed,  is  much  less  abundant  than  it  is 
in  the  nose. 


Of  the  Nerves  of  the  Pituitary  Membrane.'* 

The  pituitary  membrane  is  furnished  with  nerves  from 
two  sources;  from  the  olfactory,  and  from  the  fifth  pair. 

The  Olfactory  Nerve  having  formed  its  bulb,  which  re- 
poses in  the  ethmoidal  fossa,  sends  off  from  the  under  sur- 
face of  the  bulb,  the  succession  of  filaments  which  pene- 
trate to  the  nose  through  the  cribriform  plate.  The  latter, 
when  examined  from  the  upper  surface,  has  its  foramina  ar- 
ranged into  two  rows,  one  next  to  the  crista  galli,  and  the 
other  next  to  the  cellular  portion  of  the  ethmoid.  Each 
row  consists  of  about  six  or  eight  foramina,  and  between 
these  rows  there  are  other  foramina,  smaller,  and  not  so 
much  in  a line  with  each  other.  The  same  cribriform  fo- 
ramina, when  examined  from  the  eavity  of  the  nose,  are 
more  numerous,  especially  those  belonging  to  the  two 
rows,  in  consequence  of  the  latter  branching  out  below  into 
several  canals,  which  may  be  seen  very  distinctly  on  the 
side  of  the  base  of  the  nasal  lamella,  and  on  that  of  the  cel- 
lular portion  of  the  ethmoid. 

The  distribution  of  the  olfactory  nerve  corresponds  with 
this  arrangement  of  the  cribriform  plate,  for  it  has  three 

* Antonii  Scarpa,  Anatom.  Annotatione.s,  Lib.  ii. 


ORGAN  OF  SMELLING. 


451 


rows  of  branches  propeeding  from  the  under  surface  of  its 
bulb,  each  branch  going  through  its  appropriate  foramen, 
and  subdividing  in  it,  but  sometimes  two  filaments  pass 
through  the  same  foramen.  In  a short  space  after  their  ori- 
o-in,  they  become  invested  by  sheaths  of  the  dura  mater, 
ivdiich  are  extended  a considerable  distance,  and  by  a close 
adhesion  to  the  nerves,  make  them  appear  much  larger  be- 
low than  they  are  at  the  roots.  When  the  nerves  reach 
the  cavity  of  the  nose  they  anastomose  together,-  and  de- 
scending between  the  bone  and  the  pituitary  membrane, 
they  ramify  into  an  infinitude  of  small  branches,  the  ter- 
minating filaments  of  which  reach  the  nasal  surface  of  the 
membrane. 

The  Internal  Branches,  or  those  next  to  the  crista  galli, 
diverge  from  the  cribriform  plate,  and  pass  downward  be- 
tween the  septum  and  the  pituitary  membrane:  where  the}!- 
first  appear  in  the  nose,  there  are  some  few  adhesions  or 
anastomoses  between  them;  but  their  filaments  afterwards 
keep  perfectly  distinct,  and,  spreading  themselves  out  on 
the  pituitary  membrane  of  the  septum,  make  an  appearance 
resem.bling  a fiat  camel’s-hair  pencil.  - The  middle  ones 
are  the  longest,  and  may  be  traced  almost  to  the  floor  of  the 
nose;  the  anterior  are  shorter  somewhat;  the  posterior  do 
not  reach  obviously  below  the  middle  of  the  septum. 

The  External  Branches  have  a very  different  mode  of 
distribution.  While  still  in  their  canals  they  divide  into 
many  filaments,  which  anastomose  frequentl}^  with  each 
other,  and  when  they  have  fairly  got  into  the  cavity  of  the 
nose,  the  same  frequency  of  anastomosis  continues,  so  that 
they  form  a network  of  numerous  and  small  meshes,  which 
prevail  from  the  cribriform  plate  to  the  inferior  margin  of 
the  middle  turbinated  bone.  Their  filaments  cannot  be 
traced  below  the  latter  line,  and  therefore  do  not  descend 
so  low  as  the  filaments  of  the  internal  row,  neither  are  they 
so  close  to  each  other.  They  do  not  penetrate  to  the  eth- 
moidal cells.  The  posterior  ones  are  very  abundant  on 
the  upper  turbinated  bone,  and  incline  backwards  in  their 
descent;  the  anterior  are  also  abundant  on  the  flat  anterior 


[52 


NEKVOUS  Si'STEiX. 


half  of  the  ethmoid,  and  when  they  get  below  the  line  of 
the  upper  meatus,  they  extend  backwards  to  the  posterior 
end  of  the  middle  turbinated  bone,  and  to  its  inferior  mar- 
gin. On  this  bone  they  are  less  abundant  than  above  it; 
their  meshes  are  larger,  and  their  distribution  is  confined 
to  the  Schneiderian  membrane  covering  its  convex  surface. 

The  filaments  of  the  middle  row  associate  themselves  in- 
discriminately with  those  of  the  external  and  of  the  inter- 
nal row,  according  to  local  convenience. 

The  other  nerves  of  the  Pituitary  Membrane  come  from 
the  first  and  from  the  second  branch  of  the  Trigeminus. 
The  first  branch  gives  off  from  its  nasal  branch  the  nerve 
called  Internal  Nasal,  which  penetrates  from  the  orbit  into 
the  cavity  of  the  cranium,  through  the  anterior  internal  or- 
bitary foramen,  and  lies  covered  by  the  dura  mater,  at  the 
side  of  the  crista  galli;  thence  it  passes  into  the  cavity  of 
the  nose,  through  the  most  anterior  foramen  of  the  cribri- 
form plate. 

This  Internal  Nasal  Nerve  (Nasalis  Internus)  having 
got  into  the  nose,  divides  into  two  fasciculi,  an  internal  and 
an  external.  The  internal  descends  along  the  anterior  margin 
of  the  septum,  between  the  mucous  membrane  and  the  bone, 
and  after  a short  course  is  divided  into  two  filaments,  one 
of  which,  appl)dng  itself  to  the  posterior  face  of  the  os  nasi, 
terminates  by  smaller  filaments  in  the  integuments  of  the 
lower  part  of  the  nose;  the  other  filament  continues  along 
the  margin  of  the  septum  to  the  lower  part  of  the  latter, 
where  it  terminates  by  smaller  filaments.  The  external  fas- 
ciculus of  the  Nasalis  Internus  gives  off  early  a filament, 
which  descends  along  a groove  on  the  posterior  face  of  the 
nasal  bone,  and  winding  over  the  lower  edge  of  the  latter,  or 
passing  through  a foramen  in  it,  is  lost  upon  the  integuments 
of  the  corresponding  part  of  the  nose.  Other  filaments  from 
the  external  fasciculus  descend  upon  the  mucous  membrane, 
along  the  external  anterior  part  of  the  nose,  or  that  which 
corresponds  with  the  nasal  process  of  the  upper  maxilla. 


ORGAN  Oi'  SJIELLING. 


453 


and  terminate  near  the  anterior  extremity  of  the  inferior 
spongy  bone:  they  are  three  or  four  in  number.  The  in- 
ternal nasal  nerve,  is  also  said  to  send  one  or  more  filaments 
to  the  frontal  sinuses,  but  they  are  so  fine  that  doubts  of 
their  existence  are  entertained  by  Bichat,  though  they  are 
admitted  by  J.  F.  Meckel. 

The  Spheno-Palatine  Ganglion,  a part  of  the  second 
branch  of  the  Trigeminus,  detaches  to  the  nose,  through 
the  spheno-palatine  foramen,  several'  filaments.  One  of 
these,  discovered  by  Cotunnius,  and  admirably  delineated 
by  Scarpa  and  by  John  Hunter,  called  the  Naso  Palatinus, 
runs  across  the  front  of  the  sphenoidal  sinus  to  the  upper 
posterior  part  of  the  septum  narium,  beneath  the  mucous 
membrane.  It  then  descends  obliquely  along  the  septum 
to  the  foramen  incisivum,  and  passes  through  it  to  the  roof 
of  the  mouth.  In  many  cases,  however,  a distinct  foramen 
is  formed  in  the  middle  palate  suture  for  it,  anterior  to  the 
foramen  incisivum.  The  nerve  of  the  left  side  is  anterior 
to  that  on  the  right.  When  the  two  reach  the  roof  of  the 
mouth,  or  are  near  it,  they  unite  to  form  a little  swelling 
called  the  naso-palatine  ganglion,*  from  which  several  fila- 
ments arise,  and  are  spent  upon  the  membranous  caruncle 
at  this  point,  and  upon  the  contiguous  part  of  the  palatine 
membrane. 

The  spheno-palatine  ganglion  sends  several  filaments  to 
the  mucous  membrane  of  the  upper  spongy  bone  and  of  the 
upper  meatus,  and  to  that  of  the_  posterior  end  of  the  middle 
spongy  bone.  The  palatine  nerve,  one  of  its  largest  branches, 
in  descending  along  the  posterior  or  palatine  canal  to  the 
soft  palate  of  the  mouth,  also  contributes  to  the  supply  of 
nerves  to  the  nose.  Shortly  after  it  has  arisen  from  the 
ganglion,  it  sends  one  or  more  filaments  to  the  middle  spon- 
gy bone,  and  to  the  superior  part  of  the  lower  spongy  bone; 
and  when  it  has  got  in  its  descent  on  a level  with  the  pos- 
terior end  of  the  latter,  it  detaches  another  filament,  which 
supplies  the  mucous  membi’ane,  along  the  inferior  margin 
of  this  bone. 


* .T.  Cloquet,  loc.  clt. 


454 


NEKVOUS  SVSTEM. 


An  opinion  advanced  by  Mery  about  the  close  of  the  se- 
venteenth century,  has  lately  been  revived  by  M.  Magen- 
die,  of  Paris,  that  the  olfactory  nerves  are  not  those  which 
communicate  the  impressions  of  odorous  bodies.  In  con- 
tradiction, however,  to  his  experiments,  it  should  be  stated, 
that  several  respectable  anatomists  have  seen  cases  where 
the  privation  of  the  sense  of  smell  during  life,  was  fouftd, 
upon  examination  after  death,  to  be  attended  with  the  ab- 
sence of  the  olfactory  nerves. 

Of  the  Blood  Vessels  of  the  Nose. 

The  extreme  vascularity  of  the  Schneiderian  Membrane 
is  derived  from  several  sources.  The  Internal  Maxillary 
Artery  sends  through  the  Spheno-Palatine  Foramen  a large 
branch,  which  is  distributed  upon  the  septuhi  and  upon  the 
spongy  bones.  The  palatine  artery  also  supplies  this  mem- 
brane with  one  or  more  small  branches.  The  Ophthalmic 
also  sends  the  anterior  and  the  posterior  ethmoidal  branches 
to  it,  from  the  orbit  of  the  eye.  The  infra-orbitar  artery 
likewise  contributes  to  its  vascularity  by  one  or  more 
branches,  sent  off  in  its  course  through  the  infra-orbitar 
canal. 

The  veins  follow  the  course  and  distribution  of  the  arte- 
ries. Some  of  them,  however,  unite  with  trunks  called  the 
emissaries  of  Santorini,  which  reach  the  sinuses  of  the  brain 
through  the  foramen  ovale  and  rotundum  of  the  sphenoid 
bone. 


BOOK  IX. 


PART  IV. 

Special  Jlnatomy  of  the  JVerves, 

CHAPTER  I. 

OF  THE  NERVES  OF  THE  ENCEPHALON. 

SECT.  I. NERVDS  OPTICUS. 

The  Optic  Nerve,  as  mentioned  in  the  account  of  the 
basis  of  the  brain,  gets  into  the  orbit  by  the  optic  foramen, 
and  is  there  entirely  surrounded  by  the  origins  of  the  mus- 
cles of  the  eyeball.  It  then  describes  a slight  curvature,  of 
which  the  convexity  is  outwards,  and  runs  forwards  for  an 
inch,  when  it  penetrates  into  the  ball  of  the  eye,  where  it 
gives  origin  to  or  expands  into  the  retina.  Between  the 
muscles  and  it,  except  at  their  origins,  there  is  a mass  of 
adipose  matter. 

SECT.  II. NERVUS  MOTOR  OCULI. 

The  Nervus  Motor  Oculi,  or  third  pair,  having  reached 
from  the  basis  of  the  brain  to  the  external  side  of  the  caver- 
nous sinus,  is  placed  there  within  and  above  the  ophthalmic 
nerve  and  the  sixth  pair;  it  then  changes  its  direction,  and 
penetrates  through  the  sphenoidal  fissure  into  the  orbit,  on 
the  outer  side  of  these  nerves,  and  below  them. 

The  motor  oculi  divides,  in  the  sphenoidal  fissure,  into 
two  branches,  one  above  the  other.  The  first  crosses  over  the 


•456 


NERVOUS  SYSTEM. 


optic  nerve  and  the  nasal  branch  of  the  oplithalmic,  having 
some  anastomoses  with  the  latter,  and  then  distributes  its 
filaments  upon  the  rectus  superior  muscle;  some  of  them  also 
penetrate  the  latter  to  get  to  the  levator  palpebrie.  The 
second  branch  is  much  larger  than  the  first.  It  passes  be- 
tween the  optic  nerve  and  the  rectus  inferior  muscle,  and 
is  subdivided  into  three  fasciculi:  one  for  the  rectus  inter- 
nus  muscle;  another  for  the  rectus  inferior;  and  a thh’d, 
which  is  the  longest  and  the  smallest,  for  the  obliquus  infe- 
rior muscle.  The  latter  fasciculus,  not  far  from  its  root, 
gives  off  a filament,  which,  going  along  the  external  mar- 
gin of  the  optic  nerve,  runs  into  the  posterior  margin  of 
the  lenticular  ganglion,  and  is  its  short  root. 


SECT.  III. — NERVUS  TROCHEE ARIS. 

The  Nervus  Trochlearis,  or  fourth  pair,  having  got  into 
its  canal  in  the  cavernous  sinus,  as  it  goes  along  the  inter- 
nal margin  of  the  ophthalmic  nerve,  receives  there  a small 
filament  from  it.  ''*  It  then  rises  a little,  and  enters  the  or- 
bit at  the  internal  extremity  of  the  sphenoidal  fissure;  and 
going  forwards,  next  to  the  periosteum  of  the  upper  part  of 
the  orbit,  it  enters  into  the  superior  oblique  muscle  of  the 
eye,  near  its  middle,  and  is  distributed  upon  it.  This 
nerve  augments  in  volume  as  it  advances  towards  its  desti- 
nation. 

SECT.  IV. NERVUS  BIOTOR  EXTERNUS. 

The  Nervus  Motor  Externus,  or  sixth  pair,  having  got 
into  the  cavernous  sinus,  is  placed  there  at  the  external  side 
of  the  internal  carotid  artery,  and  adheres  closely  to  it.  It 
there  sends  off  one  or  more  filaments,  which  follow  the  in- 
ternal carotid  artery  through  its  canal  and  anastomose  in 
their  descent  Avith  a branch  of  the  pterygoid  nerve:  the 
junction  of  these  two  forms  the  upper  end  of  the  great  sym- 


Soemmering',  Icon.  OcnJ.  Human- 


NERVUS  TRiaEMINUS. 


457 


pathetic  nerve,  and  runs  down  to  the  superior  cervical  gan- 
glion of  the  sympathetic  in  two  or  more  filaments.  The 
sixth  nerve  enters  the  orbit  through  the  sphenoid  fissure, 
and  is  there  closely  connected  with  the  nervus  motor  oculi 
and  the  nasal  nerve.  It  penetrates  into  the  substance  ot  the 
rectus  externus  muscle,  and  is  entirely  distributed  upon  it; 
with  the  exception  that  sometimes  it  sends  a filament  to  the 
ophthalmic  ganglion. 


SECT.  V. OF  THE  NERVUS  TRIGEMINUS. 

This  nei’ve  having  formed  the  ganglion  of  Gasser  {Plexus 
Gangliformis)  on  the  side  of  the  petrous  bone,  then  di- 
vides, as  mentioned,  into  three  large  fasciculi,  the  foremost 
of  which  is  the  Ophthalmic  Nerve:  the  second  fasciculus 
is  the  Superior  Maxillary;  and  the  third  the  Inferior  Max- 
illary Nerve. 

The  Ophthalmic  Nerve  or  the  first  branch  of  the  trigemi- 
nus, is  smaller  than  either  of  the  other  two  branches,  and 
comes  from  the  superior  part  of.  the  plexus  gangliformis. 
It  passes  along  the  external  border  of  the  cavernous  sinus, 
and  penetrates  the  orbit  through  the  sphenoidal  fissure,  on 
the  outer  side  of,  and  near  the  motor  oculi. 

In  its  whole  course  it  is  united  to  the  trochlearis  nerve  by 
close  cellular  membrane,  and  does  not  give  off  any  ramifica- 
tions before  it  reaches  the  orbit,  with  the  exception  of  the 
filament  sent  to  the  trochlearis  nerve.  While  engaged  in 
the  sphenoidal  fissure  it  divides  into  three  branches;  the 
nasal,  the  lachrymal,  and  the  frontal. 

The  Nasal  branch  of  the  ophthalmic,  is  between  the  other 
two  in  size.  It  ascends  obliquely  above  the  optic  nerve  to 
gain  the  internal  face  of  the  orbit  of  the  eye,  and  then  passes 
forwards  just  below  the  superior  oblique  muscle,  involved 
in  a quantity  of  adipose  matter.  Shortly  after  its  origin  the 
nasal  nerve  detaches  a branch  (the  ramus  ciliaris)  which, 
situated  at  the  external  margin  of  the  optic  nerve;  runs  into 
the  ophthalmic  ganglion  and  constitutes  its  long  root;  it  then 
VoL.  II. — 58 


XERVOUS  bYSTRM. 


45^5 

sends  ofl'  one  or  more  filaments,  which,  without  communir 
eating  with  this  ganglion,  penetrate  into  the  eyeball,  and 
are  amongst  the  ciliary  nerves  which  have  been  described. 

The  nasal  nerve  continuing  to  pass  forward  along  the  in- 
ternal parietes  of  the  orbit,  when  it  reaches  the  anterior  in- 
ternal orbitary  foramen,  detaches  through  it  the  internal 
nasal  or  ethmoidal  branch,  which  thus  getting  into  the  ca- 
vity of  the  cranium,  goes  along  side  of  the  crista  galli,  and 
then  passes  into  the  nose  through  the  foremost  hole  of  the 
cribriform  plate.  It  then  descends  along  the  anterior  part  of 
the  nose,  on  the  outer  side  of  the  Schneiderian  membrane^ 
and  is  spent  by  ramifications  upon  the  contiguous  portions 
of  the  latter.  Some  of  its  terminating  branches  reach  the  tip 
of  the  nose  and  the  alae.  * 

The  nasal  nerve,  after  this  branch  is  sent  off,  is  frequently 
called  external  nasal,  or  nervus  infra-trochlearis.  It  con- 
tinues to  advance  along  the  under  margin  of  the  trochlearis 
muscle  and  gets  to  the  trochlea,  near  which  it  divides  into 
an  upper  and  an  under  ramuscle;  from  them  filaments  pro- 
ceed to  the  upper  and  under  eyelids,  to  the  lachrymal  sac, 
the  caruncle,  the  tunica  conjunctiva,  and  the  muscles  on  the 
root  of  the  nose.  These  filaments  anastomose  with  the  ter- 
minating branches  of  the  frontal  nerve,  the  facial,  and  the 
infra-orbitary.  According  to  Dr.  G.  Trasmondi,t  of  Rome, 
two  filaments  may  be  traced  very  distinctly  from  the  exter- 
nal nasal  nerve,  to  the  tensor  tarsi  muscle  of  the  lachrymal 
sac.  They  adhere  to  the  muscle  by  means  of  cellular  struc- 
ture, and  pass  on  to  its  bifurcated  extremities  and  to  the 
puncta  lachrymalia-- 

The  Frontal  Nerve  is  the  largest  of  the  three  branches 
of  the  ophthalmic.  It  proceeds  forward  between  the  levator 
palpebrse  superioris  and  the  contiguous  part  of  the  orbit,  and 
in  this  course  is  divided  into  two  branches,  the  internal  and 
the  external  frontal  nerve.  The  former  approaches  the 

* See  Nerves  of  Nose. 

f Intorno  la  scoperta  di  due  nervi  del  Occhio  umano  raggaaglio  del  Dr. 
Giuseppe  Trasmondi  Professore  di  Anatomia  Practica  nel  ven.  ospidalc 
della  Consolazione.  Roma,  1823. 


NERVU3  TRIGEMINUS. 


459 


trochlea  of  the  upper  oblique  muscle,  and  detaches  a filament 
to  join  with  one  from  the  nasal  nerve.  Other  filaments  are 
detached  to  the  upper  eyelid,  some  of  which  anastomose 
with  filaments  from  the  lachrymal  nerve.  The  internal 
branch  of  the  frontal  then  issues  from  the  orbit  just  by  the 
trochlea,  and  in  ascending  is  lost  upon  the  occipito-fi’oritalis, 
the  corrugator  supercilii,  and  the  orbicularis.  Tl^e  external 
branch  of  the  frontal  issues  from  the  orbit,  through  the 
supra-orbitary  foramen.  It  quickly  detaches  a filament, 
which  goes  outwardly  to  anastomose  with  the  facial;  the  re- 
maining part  of  the  nerv^e  is  distributed  to  the  occipito- 
frontalis, to  the  corrugator  supercilii,  to  the  integuments 
of  the  forehead,  and  to  the  scalp.  This  distribution,  accord- 
ing to  Bichat,  is  best  followed  by  detaching  the  skin,  mus- 
cles, and  periosteum,  from  the  cranium,  from  behind  for- 
wards as  far  as  the  orbit. 

The  Lachrymal  Branch  of  the  ophthalmic  nerve  goes  for- 
wards along  the  external  side  of  the  orbit  near  the  superior 
margin  of  the  rectus  externus  muscle.  In  this  course  it  sends 
ofif  a filament  through  the  spheno-maxillary  fissure  which 
unites  with  one  from  the  second  branch  of  the  fifth  pair;  it 
afterwards  sends  off  another  filament,  which  passing  through 
a foramen  in  the  malar  bone,  anastomoses  with  a filament  of 
the  facial  nerve.  What  remains  of  the  lachrymal  nerve  is 
then  distributed  by  several  filaments  upon  the  lachrymal 
gland,  the  upper  eyelid,  and  some  of  them  reach  the  con- 
junctiva. 

Seco7id  Branch  of  the  Trigeminus. 

The  Second  Branch  of  the  Fifth  Pair,  {Nervus  Maxilla- 
ris  Superior,)  arising  from  the  middle  of  the  plexus  gangli- 
formis,  or  ganglion  of  Gasser,  and  also  from  the  common 
trunk  formed  from  the  anterior  and  posterior  roots  of  the 
trigeminus,  gets  from  the  cranium  through  the  foramen  ro- 
tundum  of  the  sphenoid  bone.  While  still  in  the  cranium, 
it  sometimes  forms  an  anastomosis,  described  by  Laumonier, 
with  the  beginning  of  the  sympathetic  nerve,  but  generally 


160 


SERVOUS.  SYSTEM. 


it  docs  not  detach  any  filament  till  it  reaches  the  pterygo- 
maxillary  fossa. 

At  a short  distance  after  its  exit  from  the  cranium,  it  gives 
oifa  small  filament,  the  Nervus  Subcutaneus  Malse,  which 
ascends  into  the  orbit  through  the  spheno  maxillary  fissure, 
and  then  divides.  One  of  the  branches,  the  malar,  anasto- 
moses with  the  lachrymal  nerve,  and  leaves  filaments  with 
the  lachrymal  gland;  it  then  gets,  by  one  or  more  filaments, 
through  the  holes  of  the  malar  bone  to  the  face,  and  termi- 
nates on  the  orbicularis  muscle  and  the  skin  of  the  cheek, 
anastomosing  with  the  extremities  of  the  facial  nerve.  The 
other  branch,  the  temporal,  gets  into  the  temporal  fossa  by 
penetrating  the  internal  part  of  the  malar  bone,  and  having 
anastomosed  with  a branch  of  the  inferior  maxillary  nerve, 
it  goes  outwards  and  backwards,  becomes  superficial  by  pe- 
netrating the  temporal  aponeurosis,  and  terminates  on  the 
integuments  of  the  temple,  anastomosing  there  with  the 
branches  of  the  facial  nerve. 

The  superior  maxillary  then  divides  into  two  trunks  much 
larger  than  the  preceding,  and  of  a volume  nearly  equal;  the 
Infra-Orbital  and  the  Pterygo-Palatine. 

The  Infra-orbital  {Nervus  Infra- Orbit alis)  passes  for- 
wards, with  a slight  ascent,  to  the  posterior  part  of  the  orbit, 
and  enters  the  infra-orbitar  canal.  As  it  is  about  engaging  in 
the  latter,  it  detaches  a considerable  branch,  the  Posterior 
Dental.  This  branch  descends  a little  distance,  externally, 
along  the  posterior  parietes  of  the  maxillary  sinus,  then  pe- 
netrates into  the  cavity  of  the  latter.  It  terminates  by  fila- 
ments, some  of  which  supply  the  lining  membranp  of  the  an- 
trum ; others  pass  through  the  little  canals  leading  to  the  three 
large  grinders  and  enter  the  roots  of  the  latter;  others  go  to 
the  corresponding  gums.  One  branch  goes  along  the  outer 
side  of  the  sinus  to  anastomose  with  the  anterior  dental 
nerve.  The  posterior  dental,  before  it  enters  the  bone,  al.so 
detaches  a branch  of  some  size,  which  winds  around  the  tu- 
berosity of  the  maxillary  bone,  and  is  spent  upon  the  bucci- 
nator muscle  and  upon  the  gums. 


NERVUS  TEIGEailNUS. 


461 


The  infra-orbitary  nerve  afterwards,  in  its  course  through 
the  canal,  sends  off  the  anterior  dental  nerves  from  one  or 
more  roots.  Some  of  them  detach  fibres  to  the  mucous 
membrane  of  the  nose,  where  it  covers  the  anterior  part  of 
the  inferior  turbinated  bone.  With  this  exception,  they  are 
distributed,  through  their  appropriate  canals  in  the  bone,  to 
the  incisor  and  canine  teeth,  and  to  the  corresponding  gums. 
The  small  molar  teeth  are  most  frequently  supplied  by  a 
union  of  filaments,  from  the  anterior  and  posterior  dental 
nerves. 

The  infra-orbitar  nerve,  on  issuing  from  the  infra-orbitar 
foramen,  is  most  frequently  found  already  divided  into 
several  fasciculi,  which  may  be  classed  into  superior  and 
into  inferior.  The  former,  called  Palpebral,  radiate,  ex- 
ternally and  internally,  into  filaments  which  supply  the 
lower  eyelid.  One  of  these  filaments  may  be  traced  to  the 
end  of  the  nose,  where  it  anastomoses  with  the  internal  na- 
sal branch  of  the  ophthalmic;  another,  which  terminates 
about  the  internal  angle  of  the  eye,  anastomoses  there  with 
the  external  nasal  nerve.  Others,  of  its  terminating  fila- 
ments, anastomose  with  the  extremities  of  the  facial  nerve 
on  the  eyelid.  The  inferior  fasciculi  are  more  numerous 
and  large  than  the  superior.  They  descend  upon  the  face, 
covered  by  the  levator  muscles  of  the  upper  lip,  and  from 
their  distribution  are  called  Labial.  The  most  internal  of 
these  fasciculi  terminate  on  the  skin,  the  muscles,  and  the 
beginning  of  the  mucous  membrane  of  the  nose,  where  they 
anastomose  with  the  extremities  of  the  internal  nasal  nerve. 
The  middle  fasciculi  go  to  the  muscles  of  the  upper  lip  and 
the  skin  of  the  latter,  and  to  its  mucous  glands.  The  ex- 
ternal fasciculi  go  to  the  zygomatic  muscles  and  to  the  con- 
tiguous skin.  All  the  foregoing  branches  of  the  infra-or- 
bitar nerve  anastomose  with  the  extremities  of  the  facial, 
and  are  so  minutely  distributed  to  the  skin  and  muscles  of 
the  face,  that  it  would  require  a very  protracted  description 
to  point  them  out  particularly. 

The  Pterygo-palatine  Nerve  {Nervus  Pterygo-palqti- 
nus)  descends,  as  a single  or  a double  trunk,  from  its  I’oot 


462 


XERVOUS  SYSTEM- 


IC the  outside  of  the  spheno-palatine  foramen,  and  there 
forms  the  ganglion  of  Meckel,*  or  the  spheno-palatine  gan- 
glion, the  existence  of  which -is  not  constant.  From  this 
ganglion,  or  from  the  nerve  itself,  proceed  several  branches. 

A filament,  described  by  Bock,  is  detached  from  it,  which 
entei's  into  the  sphenoidal  sinus  to  be  distributed  on  its  li- 
ning membrane,  and  sometimes  to  anastomose  with  the  mo- 
tor externus  oculi. 

Then  arises  the  spheno-palatine  branches,  which  enter  the 
nose  through  the  spheno-palatine  foramen,  and  are  distribu- 
ted  upon  the  mucous  membrane  of  its  septum  and  turbina- 
ted portions,  after  the  manner  described  in  the  account  of 
the  nose. 

From  the  inferior  part  of  the  ganglion  arises  a recurrent 
branch  {Nervus  J^idianus,recurrens,  pter^goideus)  which 
goes  backwards  through  the  pterygoid  foramen  of  the  sphe- 
noid bone.  From  it  there  arise  some  filaments,  which  get 
to  the  mucous  membrane  about  the  anterior  orifice  of  the 
Eustachian  Tube,  either  through  the  spheno-palatine  fora- 
men, or  by  small  foramina  in  the  pterygoid  process  of  the 
sphenoid  bone.  They  are  sometimes  united  into  a single 
trunk,  called  pharyngeal  by  Bock.  The  vidian  nerve, 
while  still  in  its  canal,  then  divides  into  two  trunks,  the 
superficial,  and  the  deep  petrous. 

The  Superficial  Petrous  {Nervus  Pctrosus  Superficialis) 
traverses  the  cartilaginous  matter  at  the  point  of  the  petrous 
bone,  in  the  anterior  foramen  lacerum  of  the  basis  of  the  cra- 
nium, gets  there  into  the  cavity  of  the  lattei’,  continues  its 
pi’ogress  backwards  on  the  superior  face  of  the  petrous  bone, 
in  a gutter  marked  on  the  bone,  and  disappears  through  the 
vidian  foramen.  It  in  a short  space  reaches  the  aqueduct 
of  Fallopius,  and  then  continues  to  adhere  to  the  facial  nerve 
till  the  latter  almost  reaches  the  stylo-mastoid  foramen j it 
then  abandons  the  facial  nerve,  and,  as  mentioned  in  the 
account  of  the  ear,  traverses  the  tympanum  under  the  name 
of  chorda  tympani,  and  finally  emerging  at  the  glenoid  fora- 
men, it  runs  to  associate  itself  with  the  lingual  branch  of 

* Discovered  by  Meckel,  3749. 


NERVUS  TRiaEMINUS. 


463 


the  trigeminus.  The  superficial  petrous  in  the  early  part 
of  its  course,  at  the  point  of  the  petrous  bone  detaches  one 
or  more  filaments  to  the  sympathetic  in  the  carotid  canal. 

The  Deep  Petrous  [Nervus  Petrosus  Profundus)  is 
larger  than  the  other.  It  also  penetrates  through  the  car- 
tilaginous matter  at  the  point  of  the  petrous  bone,  and  en- 
ters the  cavity  of  the  cranium  under  the  dura  mater.  It 
then  advances  to  the  internal  carotid  artery,  and  anasto- 
moses there  with  a filament  from  the  motor  externus.  This 
anastomosis  is  commonly  cailed  the  beginning  of  the  sym- 
pathetic nerve. 

The  Palatine  Nerve  {Nervus  Palatinus,  naso-palaii- 
nus)  proceeds  from  the  inferior  part  of  the  ganglion  of 
Meckel,  and  gets  to  the  soft  palate  of  the  mouth  through 
the  posterior  palatine  foramen.  In  this  course  it  detaches 
several  filaments  to  the  Schneiderian  membrane,  which  reach 
it  either  through  the  spheno-palatine  foramen  or  by  perfo- 
rating the  nasal  lamella  of  the  palate  bone.  These  are  de- 
sci'ibed  in  the  account  of  the  nose. 

The  trunk  of  the  palatine  nerve,  having  reached  the  roof 
of  the  mouth,  bends  forwards,  and  is  divided  into  many 
filaments,  some  of  which  are  distributed  along  the  gums  of 
the  upper  jaw  otliers  are  distributed  on  the  lining  mem- 
brane of  the  hard  palate  and  upon  its  mucous  glands. 

There  are  two  other  nerves,  which  arise  either  immedi- 
ately from  the  palatine,  or  from  the  ganglion  of  Meckel, 
and  go  to  supply  the  soft  palate.  They  are  called  the 
smaller  palatine.  One  of  them,  having  proceeded  for  a 
short  distance  in  the  posterior  palatine  canal,  departs  from 
it  in  a little  canal  of  its  own,  which  opens  behind  the  hook 
of  the  internal  pterygoid  process.  It  then  radiates  into 
filaments,  which  supply  the  tonsil  gland  and  the  muscular 
and  membranous  structure  of  the  soft  palate.  The  other 
smaller  palatine  also  traverses,  after  the  same  manner,  its 
own  canal,  and  is  likewise  distributed  to  the  tonsil  gland 
and  to  the  soft  palate. 


464 


NERVOUS  SYSTEM. 


Third  Branch  of  the  Trigeminus. 

The  Third  Branch  of  the  Trigeminus  (^Nervus  Infra- 
maxillaris)  is  the  largest  of  the  three.  It  arises  from  the 
posterior  inferior  part  of  the  ganglion  of  Gasser,  and  having 
anasjtomosed  with  the  cavernous  ganglion  of  the  sympathe- 
tic nerve  by  filaments,  which  are  not  constant,  it  emerges 
from  the  cranium  through  the  foramen  ovale  of  the  sphe- 
noid bone.  A portion  of  this  branch  does  not  enter  into 
the  composition  of  the  ganglion  of  Gasser,  but  proceeds 
immediately  from  the  pons  varolii. 

The  inferior  maxillary  nerve,  at  its  exit  from  the  fora- 
men ovale,  is  covered  by  the  pterygoideus  externus  muscle, 
and  commonly  divides  there  into  two  branches,  one  ante- 
rior and  the  other  posterior. 

The  anterior  branch,  which  is  much  smaller  than  the 
other,  radiates  into  five  fasciculi;  the  masseter  nerve,  the 
two  temporal;  the  buccal;  and  the  pterygoid. 

a.  The  Masseter  Nerve  is  directed  horizontally  outwards 
and  backwards,  along  the  external  margin  of  the  pterygoi- 
deus externus,  and  in  front  of  the  temporo-maxillary  arti- 
culation: it  leaves  some  filaments  with  the  lattei’,  and  then 
passing  between  the  insertion  of  the  temporal  and  of  the 
external  pterygoid  muscles,  over  the  concave  edge  of  the 
bone,  between  the  condyle  and  the  coronoid  process  of  the 
lower  jaw,  it  passes  into  the  substance  of  the  masseter  mus- 
cle, and  is  distributed  through  it. 

b.  The  two  Temporal  branches  arise  by  a common  fasci- 
culus, but  sometimes  differently.  They  pass  outwards  ho- 
rizontally between  the  external  pterygoid  muscle  and  zy- 
gomatic fossa.  They  then  ascend  on  the  side  of  the  tem- 
poral bone,  between  it  and  the  temporal  muscle,  and  are 
distributed  through  the  latter  by  a great  number  of  fila- 
ments. Some  of  these  filaments  penetrate  the  aponeurosis, 
to  anastomose  with  the  superficial  temporal  nerves.  And  one 
of  them  anastomoses  with  that  branch  of  the  superior  max- 
illary which  sends  filaments  to  the  lachrymal  gland,  and 


NERVUS  TRIGtEMINUS. 


465 


afterwards  escapes  from  the  orbit,  through  the  foramina  in 
the  malar  bone,  into  the  temporal  fossa.  It  is  at  the  latter 
place  that  the  anastomosis  occurs. 

c.  The  Buccal  Branch  is  the  largest  of  the  five.  It  ad- 
vances between  the  pterygoid  muscles,  to  which  it  fur- 
nishes a few  filaments,  and  then  descends  between  the  tem- 
poral and  external  pterygoid  muscle,  to  the  posterior  part 
of  the  buccinator.  It  is  principally  distributed  on  the  lat- 
ter, upon  the  buccal  glands,  and  the  corresponding  part  of 
the  lining  membrane  of  the  mouth.  Some  of  its  branches 
advance  under  the  integuments  of  the  face,  as  far  as  the 
commissure  of  the  lips  to  the  muscles  there,  and  anastomose 
with  the  facial  nerve. 

(1.  The  Pterygoid  Branch  is  tlie  smallest,  and  is  distri- 
buted principally  on  the  internal  pterygoid  muscle. 

The  posterior  branch  of  the  inferior  maxillary  nerve  is  so 
large,  that  it  looks  like  a continuation  of  the  trunk.  It  is 
divided  into  the  superficial  temj^oral,  the  inferior  dental, 
and  the  lingual  nerves. 

a.  The  Superficial  Temporal  Branch  is  formed  by  a 
union  of  two  fasciculi,  between  which,  passes  the  middle 
artery  of  the  dura  mater;  the  inferior  of  these  fasciculi 
comes  from  the  inferior  dental  nerve.  The  nerve  is  di- 
rected outwardly,  and  winds  horizontally  around  the  poste- 
rior face  of  the  neck  of  the  condyle  of  the  lower  jaw,  be- 
tween it  and  the  meatus  auditorius  externus.  It  is  there  di- 
vided into  several  small  fasciculi,  two  or  three  of  which  pene- 
trate into  the  substance  of  the  parotid  gland,  and  anastomose 
with  the  facial  nerve  or  its  ramifications;  one  or  two  others 
go  backwards,  penetrate  between  the  bony  and  the  cartila- 
ginous meatus  to  the  auditory  canal,  and  are  disj>ersed  by 
fine  filaments  upon  the  concha,  and  the  meatus  externus. 
According  to  Bock,  one  of  these  filaments  supplies  the 
membrane  of  the  tympanum,  and  also  anastomoses  with  the 
chorda  tympani.  Another  branch  of  the  superficial  tempo- 
ral, which  is  the  largest  of  any,  traverses  the  parotid  gland, 
and  thereby  becomes  superficial,  just  in  front  of  the  exter- 
nal ear.  It  then  divides  into  filaments,  which  follow  the 

VoL.  II. — 59 


46b 


NERVOUS  SYSTEM. 


course  of  the  superficial  temporal  artery,  and  thereby  sup- 
ply the  middle  part  of  the  integuments  on  the  side  of  the 
head.  It  anastomoses  with  the  filaments  of  the  frontal 
nerve,  and  with  those  of  the  occipital. 

h The  Inferior  Dental  Nerve  is  placed  between  the  other 
two  branches,  and  exceeds  them  in  size.  It  descends  be- 
tween the  two  pterygoid  muscles,  towards  the  posterior 
mental  foramen.  Just  above  tho  latter  it  detaches  a small 
branch,  the  mylo-hyoid,  which  occupies  the  small  gutter 
on  the  bone  leading  downward  from  the  posterior  mental 
foramen.  This  branch  sends  a filament  to  the  submaxillary 
gland,  then  passes  between  the  anterior  belly  of  the  digas- 
tric muscle  and  the  mylo-hyoideus,  to  both  of  which  it 
gives  filaments,  and  finally  winding  over  the  base  of  the 
lower  jaw  in  front,  it  is  lost  upon  the  muscles  of  the  chin. 

The  inferior  dental  nerve  then  enters  the  posterior  men- 
tal foramen,  and  divides  into  two  branches,  which  run  pa- 
rallel with  one  another,  through  the  canal  in  the  middle  of 
the  spongy  structure  of  the  bone,  and  send  a great  number  of 
anastomotic  filaments  to  each  other.  One  of  the  branches, 
the  dental,  properly  speaking,  as  it  passes  along  the  ends  of 
the  roots  of  the  teeth,  detaches  a filament  to  each  root, 
from  the  last  grinder  to  the  first  incisor  tooth  inclusively; 
it  also  sends  a filament  to  the  gum  intermediate  to  every  two 
teeth.  All  of  these  filaments  arise  from  the  dental  nerve,  at 
places  behind  the  points  of  destination,  so  that  they  have, 
before  reaching  the  latter,  to  run  forwards  and  upwards 
through  little  canals  in  the  cellular  structure  of  the  bone. 

The  other  branch  of  the  inferior  dental  nerve  is  the  men- 
tal; it  does  not  advance  so  far  forward  in  the  bone  as  the 
preceding,  but  issues  from  it  at  the  anterior  mental  fora- 
men, and  immediately  is  divided  into  two  fasciculi,  the  in- 
ferior labial  nerves.  The  internal  fasciculus  is  distributed 
by  filaments  upon  the  muscles  of  the  chin  and  lower  lip, 
the  contiguous  lining  membrane  of  the  mouth  and  the  la- 
bial glands.  The  external  fasciculus  rises  upwards  and  is 
distributed  on  the  muscular  structure,  about  the  under  part 
of  the  commissure  of  the  lip,  and  to  the  contiguous  lining 
membrane  and  glands  of  the  mouth. 


NERVUS  TRIGEMINUS. 


467 


c.  The  Lingual  Nerve  descends  in  company  with  the  in- 
ferior dental,  but  in  advance  of  it  and  diverging  slightly. 
While  between  the  two  pterygoid  muscles  it  receives  the 
chorda  tympani  at  a very  acute  angle.  It  then  passes  to- 
wards the  side  of  the  root  of  the  tongue,  deeply  concealed 
by  the  angle  of  the  lower  jaw,  and  above  the  submaxillary 
gland,  to  wiiich  it  gives  some  considei'able  filaments.  Oc- 
casionally, however,  a ganglion,  called  the  maxillary,  is 
formed  here  by  one  or  more  filaments  of  the  lingual  nerve, 
and  from  this  ganglion  proceed  filaments  to  the  submaxilla- 
ry gland. 

The  lingual  nerve  then  proceeds  forwards  between  the 
mylo-hyoideus  and  the  hyo-glossus  muscle,  and  between  the 
sublingual  gland  and  the  latter,  having  in  front  of  it  the 
excretory  duct  of  the  submaxillary  gland.  It  anastomoses 
frequently  with  the  hypo-glossal  nerve,  sends  several  fila- 
ments to  the  lining  membrane  of  the  mouth,  below  the 
tongue,  and  to  the  sublingual  gland.  It  then  divides,  or 
radiates,  into  seven  or  eight  fasciculi,  which  run  upwards 
and  forwards  on  the  side  of  the  stylo-glossus  muscle,  and 
are  finally  spent  upon  the  side  and  the  tip  of  the  tongue, 
by  very  fine  filaments  penetrating  into  the  structure  of  the 
papillae. 

The  tensor  tympani  muscle  is  supplied  by  a nerve  called 
Auricular  by  its  discoverer.  Dr.  Arnold,  coming  from  a 
ganglion  near  the  foramen  ovale  formed  by  filaments  from 
the  inferior  maxillary  nerve.  This  ganglion  is  below  the 
spinous  process  of  the  sphenoid  bone,  and  sends  off  several 
filaments,  one  contributes  to  the  nervous  anastomosis  of  Ja- 
cobson, which  connects  the  superior  maxillary,  glosso-pha- 
ryngeal,  and  sympathetic  nerves;  the  other  filament  passes 
to  the  tensor  tympani  and  is  distributed  upon  it.  Other 
filaments  join  the  superficial  temporal  nerve,  that  part  of  it 
which  supplies  the  membrana  tympani.  There  is  also  an 
anastomosis  with  the  portio  mollis.* 


Am,  Med.  Jour.  vol.  v.  p.  192. 


JSERVOUS  SYSTEM. 


SECT.  VI. — NERVES  FACIALIS. 

The  Facial  Nerve  (^Nervus  Facialis;  poy'tio  dura  septi- 
mi;  par  sepLirnum)  having  gained  the  meatus  auditories 
internus,  passes  in  front  of  the  auditory  nerve  into  the  canal 
of  Fallopius,  and  winding  through  it,  around  the  tympa- 
num, it  emerges  at  the  stylo-mastoid  foramen,  having  sent 
in  this  course  one  or  more  filaments  to  the  muscles  of  the 
little  bones  of  the  tympanum. 

Afterwards,  the  facial  nerve  gives  off  several  branches, 
which  are  distributed  as  follows: 

a.  The  posterior  auricular  nerve  arises  near  the  foramen, 
and  having  sent  several  filaments  into  the  mastoid  process, 
it  winds  over  the  anterior  face  of  the  base  of  the  latter,  and 
divides  into  two  fasciculi.  The  anterior  is  distributed  in 
filaments  upon  the  back  of  the  external  ear,  the  cartilaginous 
meatus,  and  the  posterior  auris  muscle;  the  posterior  ascends 
upon  the  mastoid  portion  of  the  temporal  bone  to  the  pos- 
terior belly  of  the  occipito-frontalis  muscle,  and  is  spent  by 
filaments  to  the  latter,  and  to  the  corresponding  integu- 
ments, anastomosing  likewise  with  ramifications  of  the  oc- 
cipital nerve. 

b.  The  facial  nerve  then  detaches  filaments  to  the  mus- 
cles of  the  styloid  process,  and  to  the  posterior  belly  of  the 
digastric  muscle.  It  also  sends  filaments  of  anastomosis  to 
the  superior  part  of  the  sympathetic  nerve;  to  the  cutaneous 
cervical:  and  to  ramifications  of  the  glosso-pharyngeal;  of 
the  pneumo-gastric,  and  of  the  accessory. 

The  facial  nerve,  having  given  off  the  foregoing  filaments 
and  branches,  penetrates  downwards  and  forwards  into  the 
substance  of  the  parotid  gland,  where  it  is  divided  into  a 
number  of  branches,  varying  from  two  to  five,  which  form 
a plexus  by  their  anastomosis.  This  plexus  is  reenforced, 
as  mentioned,  by  branches  from  the  superficial  temporal  of 
the  inferior  maxillary,  which  wind  around  the  neck  of  the 
lower  jaw.  It  is  then  distributed  to  the  side  of  the  face  in 


;SERVUS  FACIALIS. 


4t)L» 

radiating  clusters  or  columns  of  filaments,  called  the  tempo- 
ro-facial,  the  buccal,  and  the  cervico-facial. 

The  Temporo-facial  Nerves  or  Branches,  are  hid  for  some 
distance  in  the  upper  part  of  the  parotid  gland,  which  they 
traverse  below  the  neck  of  the  lower  jaw.  They  divide 
into  filaments,  some  of  which  go  to  the  temple,  and  others 
to  the  cheek.  The  temporal  branches  are  commonly  two 
or  three  in  number;  they  leave  filaments  with  the  parotid 
gland,  mount  over  the  zygoma,  and  are  distributed  to  the 
anterior  auris  muscle,  to  the  outer  section  of  the  orbicula- 
ris palpebrarum,  and  to  the  integuments  of  the  temple;  they 
anastomose  in  their  distribution  with  each  other,  with  the 
superficial  and  deep  temporal  branches  of  the  inferior  max- 
illary nerve,  and  with  the  frontal  and  lachrymal  branches 
of  the  ophthalmic.  The  malar  branches  are  primitively,  also, 
two  or  three  in  number;  they  cross  the  malar  bone,  divid- 
ing, subdividing,  and  anastomosing  again,  and  are  spent  upon 
the  integuments  and  muscles  of  this  part  of  the  face.  They 
also  anastomose  with  filaments  of  the  lachrymal  nerve,  and 
with  those  of  the  infra-orbitar  nerve. 

The  Buccal  Branches  are  three  in  number,  sometimes  two 
only;  and  pass  across  the  masseter  muscle  under  the  skin. 
The  superior  anastomoses  with  the  temporo-facial,  and  the 
inferior  with  the  cervico-facial.  The  buccal  branches  sup- 
ply the  skin  and  muscles  of  the  face  intermediate  to  the 
eye  and  to  the  lower  lip.  The  numerous  filaments  into 
which  they  divide  anastomose  frequently  with  each  other, 
and  with  the  branches  of  the  fifth  pair,  which  appear  about 
the  same  parts,  as  the  external  and  internal  nasal  nerve, 
the  infra-orbitar,  and  so  on.  The  middle  buccal  is  parallel 
with  the  duct  of  the  parotid  gland  and  adheres  to  it. 

The  Cervico-facial  Branch  descends  in  the  substance  of 
the  parotid  gland,  behind  the  ramus  of  the  lower  jaw;  wdien 
it  reaches  the  angle  of  the  latter  it  goes  obliquely  forwards, 
beneath  the  platysma  myoides  muscle.  Though  it  sends 
off  many  fasciculi,  they  may  be  referred  to  two  divisions, 
a superior,  and  an  inferior.  The  first  crosses  the  inferior 
part  of  the  masseter  muscle,  and  may  be  traced  in  its  nu- 


470 


NERVOUS  SYSTEM. 


merous  distribution  of  filaments,  to  the  integuments  and 
muscles  lying  upon  the  body  of  the  lower  jaw.  These 
filaments  anastomose  with  each  other,  and  with  the  mental 
branches  of  the  inferior  dental  nerve.  The  inferior  division 
supplies  the  skin  and  the  platysma  myoides  muscle  of  the 
upper  part  of  the  neck  along  the  base  of  the  lower  jaw.  Its 
filaments  are  joined  by  several  coming  from  the  anterior 
fasciculus  of  the  Lhirrt  cervical  nerve. 

The  anastomoses  of  the  facial  nerve,  derived  from  its  own 
branches  and  from  those  of  the  trigeminus,  which  reach  the 
face  are  entirely  too  numerous  for  a detailed  description  of 
them,  it  indeed  appears  unnecessary  to  extend  the  latter  be- 
yond a certain  point.  The  most  satisfactory  account  has 
been  published  by  Meckel.* 

SECT.  VII. — NERVUS  HYPOGLOSSUS. 

The  Hypo-glossal  Nerve  {Nervus  Hypoglossus,  Lin- 
gualis)  having  arisen  from  the  medulla  oblongata,  and  es- 
caped from  the  cranium  through  the  anterior  condyloid  fo- 
ramen, adheres  closely  for  an  inch  to  the  pneumogastric 
nerve.  It  descends  between  the  external  carotid  artery  and 
the  internal  jugular  vein,  the  latter  being  behind  the  other, 
and  then  winds  over  the  carotid  externally,  just  below  the 
origin  of  the  occipital  artery.  It  is  there  covered  by  the 
posterior  belly  of  the  digastricus  and  by  the  stylo-hyoideus. 
It  then  passes  forwards  beneath  the  external  jugular  vein, 
and  lower  down  somewhat  than  the  tendon  of  the  digastric 
muscle,  and  finally  ascends  to  the  tongue,  being  covered  or 
concealed  by  the  mylo-hyoideus  muscle.  The  nerve  in  this 
course,  from  the  external  carotid  to  the  tongue,  forms  a re- 
markable curve,  the  convexity  of  which  is  downwards. 

The  Hypo-glossal,  while  adhering  to  the  par  vagum, 
com.monly  leaves  a few  filaments  with  it.  As  it  crosses 
the  external  carotid  it  detaches  a large  branch,  the  Ramus 
Descendens  Noni,  which  goes  down  the  neck,  along  the 

* J.  F.  Meckel,  de  nervis  faciei,  Mem.  de  I’Acad.  de.s  S.  de  Berlin,  1751. 
Caldani,  Tab.  247- 


NERVUS  HYPOGLOSSUS. 


471 


sheath  of  the  carotid  artery  and  the  internal  jugular  vein, 
in  front  of  the  latter. 

The  ramus  descendens  has  been  beautifully  figured  by 
Scarpa,  in  his  Plates  of  the  Nerves.  According  to  him, 
when  it  has  got  about  half  way  down  the  neck,  but  still 
resting  on  the  sheath  of  the  vessels,  it  detaches  in  front  two 
filaments,  which,  after  the  course  of  an  inch  forwards  unite, 
and  then  separate  again  to  be  distributed  to  the  upper  ends 
of  the  omo-hyoid  and  sterno-hyoid  muscles.  The  descen- 
dens noni  then  forms,  an  inch  lower  down,  a small  gangli- 
form  plexus,  resting  upon  the  sheath  of  the  great  vessels 
of  the  neck,  under  the  omo-hyoid  muscle.  This  plexus 
is  joined  by  two  fasciculi,  which  descend  from  the  first  and 
second  cervical  nerves,  and  from  it  proceed  downwards  and 
backwards,  two  filaments,  which  join  the  phrenic  nerve; 
also  one  to  the  lower  part  of  the  omo-hyoid  muscle;  and 
three  or  more,  which  are  divided  and  distributed  upon  the 
sterno-hyoid  and  thyroid  muscles,  and  upon  the  muscles  of 
the  larynx.  Meckel  states,  that  some  of  these  ramifica- 
tions, on  the  left  side  principally,  penetrate  to  the  thorax, 
and  reach  the  pericardium. 

The  hypo-glossal  nerve,  having  sent  off  the  ramus  descen- 
dens, reaches  the  external  face  of  the  hyo-glossus  muscle, 
and  is  there  concealed  by  the  mylo-hyoideus,  where  it  gives 
filaments  to  the  muscles  of  the  larynx,  to  the  hyo-glossus, 
genio-hyoideus,  and  genio-hyoglossus.  These  filaments 
anastomose  frequently  with  each  other,  and  in  two  or  three 
places  at  the  anterior  part  of  the  tongue  with  a lingual  branch 
of  the  nervus  trigeminus.  After  these  branches  are  given 
off,  the  trunk  of  the  hypo-glossal  nerve  penetrates  into  the 
substance  of  the  genio-hyo-glossus  muscle,  and  extends  it- 
self near  its  fellow,  and  not  far  from  the  middle  line  of 
the  tongue  to  the  point  of  the  latter.  It  first  distributes  fila- 
ments near  the  posterior  part  of  the  tongue,  and  then  suc- 
cessively as  far  as  its  anterior  extremity.  They  cannot  be 
traced  to  the  papillae  but  are  lost  upon  the  muscular  struc- 
ture. 

It  is  a general  opinion  among  anatomists  that  the  hypo- 
glossal nerve  is  only  intended  to  excite  the  muscular  move- 


47.3 


NERVOUS  SYSTEM. 


mcnls  of  the  tongue.  The  opinion  is  founded  upon  the  cir- 
cumstance of  its  filaments  not  reaching  the  papillse,  whereas 
those  of  the  lingual  branch  of  the  trigeminus  do.  Colombo 
narrates  a case,  in  which  there  was  a congenital  privation  of 
taste,  where  the  lingual  branch  of  the  trigeminus  was  dis- 
tributed upon  the  occiput  instead  of  upon  the  tongue,  which 
goes  far  to  prove  the  difference  of  function  in  the  two 
nerves. 


SECT.  Till. NERVUS  ACCESSORIUS. 

The  Accessory  Nerve  (^Nervus  Accessorius,  JVillisii) 
having  arisen,  as  described,  from  the  cervical  medulla  and 
the  medulla  oblongata,  is  directed  outwards  to  the  posterior 
foramen  lacerum,  in  company  with  the  pneumo-gastric  or 
par  vagum.  Sometimes  it  is  separated  from  it  in  its  passage 
through  the  base  of  the  cranium,  by  a thin  partition  of  dura 
mater,  on  other  occasions  merely  by  a fold  of  the  tunica 
arachnoidea,  but  at  the  inferior  part  of  this  foramen  it  ad- 
heres so  closely  to  the  par  vagum  that  the  two  look  like  but 
one  nerve. 

Near  its  exit  it  is  divided  into  two  fasciculi.  The  most 
internal  gives  off  one  or  two  filaments,  which,  joining  a 
branch  of  the  par  vagum,  forms  the  superior  pharyngeal 
nerve;  the  internal  branch  then  descends,  and  being  divided 
into  several  branches,  they  successively  join  the  upper  part 
of  the  par  vagum.  The  external  fasciculus  descends  for 
two  inches  behind  the  internal  jugular  vein,  being  placed 
first  of  all  between  it  and  the  occipital  artery,  but  subse- 
quently between  the  vein  and  the  sterno-mastoid  muscle. 
It  then  pierces  the  muscle  about  one-third  of  the  length  of 
the  latter  from  its  superior  extremity,  and  leaves  filaments 
in  it  which  anastomose  with  some  from  the  third  cervical 
nerve.  In  continuing  its  descent  it  is  re-enforced  and  aug- 
mented considerably  in  volume  by  branches  from  the  se- 
cond and  third  cervical.  Having  reached  the  anterior  mar- 
gin of  the  trapezius  muscle,  it  then  distributes  itself  to  the 
latter,  by  internal  and  by  external  branches. 


473 


GLOSSO-PHARYNGEAL  NERVE. 


SECT.  IX. NERVUS  GLOSSO-PHARYNGEUS. 

The  Glosso-Pharyngeal  Nerve  (Nervus  Glosso-Pharyn- 
geus,)  though  commonly  considered  as  distinct  from  the 
pneumo-gasti’ic,  has  so  many  connexions  with  it,  both  at  its 
root,  in  its  course  through  the  posterior  foramen  lacerum, 
and  in  its  distribution,  that  it  seems  like  a part  or  branch  of 
the  same.  Before  it  enters  the  canal  of  the  dura  mater, 
which  conducts  it  through  the  base  of  the  cranium  in  front 
of  the  pneumo-gastric,  it  forms,  according  to  some  anato- 
mists,* a ganglion  of  five  or  six  lines  in  length,  the  exist- 
ence of  which  is  denied  by  Bichat.  From  this  ganglion 
proceeds  a filament!  which  penetrates  into  the  tympanum, 
and  divides  into  two  branches;  one  of  them  ascends  along 
the  promontory,  having  detached  a filament  to  the  membrane 
of  the  foramen  rotundum;  it  then  penetrates  the  petrous 
bone;  and  anastomoses  or  joins  with  the  superficial  petrous 
nerve.  The  other  branch  passes  below  the  bony  Eustachian 
Tube,  and  gaining  the  carotid  canal  anastomoses  there  with 
the  Sympathetic  Nerve.  The  ganglion  also  gives  off  other 
filaments,  which  traverse  the  canal  of  the  dura  mater,  to 
join  the  pneumo-gastric  nerve,  the  accessory  and  the  sym- 
pathetic. 

On  issuing  from  the  posterior  foramen  lacerum,  the  glosso- 
pharyngeal is  separated  from  the  pneumo-gastric  by  the  in- 
ternal jugular  vein.  It  is  then  directed  downwards  and 
forwards  between  the  internal  carotid  and  the  stylo-pha- 
ryngeus  muscle;  afterwards  between  the  latter  and  the 
stylo-glossus;  it  follows  the  direction  of  the  latter  to  the 
side  of  the  root  of  the  tongue. 

In  this  course  it  sends  off  many  filaments.  Shortly  after 
leaving  the  cranium  it  detaches  one  backwards  to  the  digas- 
tric branch  of  the  facial,  and  another  to  the  pneumo-gas- 
tric. It  then  sends  off  two  filaments,  which  descend  along 

* Andersech  and  Huber, 
j RosenmuUer,  Jacobson,  Lobsteiu. 

VoT..  TI. — 60 


■171 


NERVOUS  SYSTEAX. 


the  internal  and  the  common  carotid,  and  are  divided  into 
several  branches,  some  of  which  anastomose  with  the  pha- 
ryngeal branch  of  the  pneumo-gastric,  others  descend  on  the 
coirimon  carotid  with  filaments  from  the  pharyngeal  branch, 
and  being  joined  by  two  or  three  small  twigs  from  the  supe- 
rior cervical  ganglion,  they  reach  the  lower  part  of  the  neck, 
and  concur  in  the  forming  of  the  superficial  cardiac  nerve. 
Further  down  after  the  origin  of  these  branches  the  glosso- 
pharyngeal detaches  two  or  three  filaments  to  the  stylo- 
pharyngeus  muscle,  as  well  as  some  to  the  upper  and  middle 
constrictors  of  the  pharynx,  to  the  pharyngeal  plexus  of  the 
sympathetic  and  pneumo-gastric,  and  to  the  posterior  lateral 
and  superficial  part  of  the  tongue. 

The  glosso-pharyngeal  nerve  having  got  between  the 
stylo  and  hyo-glossus  muscles,  is  placed  intermediately  to 
the  lingual  branch  of  the  fifth  pair  and  the  hypo-glossal 
nerve.  Some  of  its  branches  then  go  to  the  integuments  of 
the  base  of  the  tongue,  to  its  mucous  glands,  large  papillae, 
and  may  be  traced  to  the  mucous  membrane  of  the  soft  pa- 
late, to  the  amygdalae,  and  to  the  covering  membrane  of  the 
epiglottis.  Others  go  into  the  muscles  of  the  tongue,  and 
others  may  be  traced  along  the  external  margin  of  the 
tongue,  beneath  its  mucous  membrane  for  some  distance. 
Scarpa  has  delineated  a remarkable  plexus,  which  he  deno- 
minates Circulus  Tonsillaris  Anderschii  or  Anastomosis 
Plexuosa,  formed  by  these  several  filaments  and  by  branches 
of  the  lingual,  on  the  side  of  the  root  of  the  tongue,  at  the 
base  of  the  tonsil  gland. 


SECT.  X. — NERVUS  PNEUMO-GASTRICUS. 

The  Pneumo-gastric  Nerve  (Nervus  Pneumogastricvs, 
Vagus,  Par  Octavum,  Decimum  of  Jindersech)  at  its  exit 
from  the  cranium  through  the  posterior  foramen  lacerum, 
in  front  of  the  internal  jugular  vein,  is  closely  united  to  the 
hypo-glossal,  glosso-pharyngeal,  and  accessory  nerves,  by 
compact  cellular  substance.  It  is  first  placed  in  front  of  the 
hypo-glossal  nerve,  but  in  a short  space  gets  behind  it,  and 


PNEUMO-GASTRIC  NERVE. 


475 


is  also  separated  from  the  glosso-pharyngeal  by  the  internal 
jugular  vein.  Opposite  the  transverse  process  of  the  atlas, 
it  leaves  the  hypo-glossal  nerve,  and  assumes  a position  be- 
tween the  internal  carotid  and  the  internal  jugular,  on  the 
vertebral  side  of  these  vessels,  and  is  enveloped  in  their 
sheath  of  dense  cellular  substance.  It  maintains  this  relative 
position  along  the  common  carotid  to  the  root  of  the  neck. 

At  the  latter  place  the*  pneumcv-gastric  of  the  right  side 
goes  in  front  of  the  subclavian  artery  near  its  root,  but  on  the 
left  side  it  crosses  the  root  of  the  left  subclavian  artery,  and 
the  arch  of  the  aorta  to  the  left  of  the  origin  of  the  left  ca- 
rotid. In  getting  fairly  into  the  cavity  of  the  thorax,  it 
is  directed  backwards  and  downwards  from  these  points, 
towards  the  posterior  face  of  the  bronchia,  between  it  and 
the  pleura.  It  then  abandons  the  bronchia,  and  applies  itself 
to  the  oesophagus,  and  follows  it  through  the  diaphragm 
to  the  stomach.  The  nerve  of  the  left  side,  in  its  course 
along  the  oesophagus,  is  on  the  front  surface  of  the  latter, 
and  the  nerve  of  the  right  side  on  its  posterior  surface. 

The  pneumo-gastric  anasto  . ;oses  with  the  accessory  while 
passing  through  the  foramen  lacerum  posterius.  Somew'hat 
lower  down,  it  also  anastomoses  with  the  glosso-pharyngeal 
and  with  the  superior  cervical  ganglion  of  the  sympathetic. 
The  branches  which  it  afterwards  sends  off,  go  to  the  neck, 
to  the  viscera  of  the  thorax,  and  to  those  of  the  abdomen, 
after  the  following  manner: 

A.  Cervical  Branches.  The  Superior  Pharyngeal  Nerve 
{JRamus  Pharyngeus)  arises  just  below  the  preceding  anas- 
tomosis. It  is  directed  downwards  on  the  internal  face  of 
the  internal  carotid,  and  having  sent  an  anastomotic  filament 
to  the  glosso-pharyngeal  nerve,  it  forms  on  the  middle  con- 
strictor of  the  pharynx,  the  pharyngeal  plexus  which  is  re- 
enforced by  filaments  from  the  superior  cervical  ganglion 
of  the  sympathetic,  from  the  glosso-pharyngeal,  and  from 
the  superior  laryngeal  nerve.  The  filaments  departing  from 
this  plexus,  are  spent  principally  upon  the  middle  constrictor, 
but  a few  of  them  also  go  to  the  superior  constrictor;  and 
others,  descending  along  the  primitive  carotid,  anastomose 


KEKVOUS  SVfaTEJVI. 


47(j 

with  ramifications  from  the  glosso-pharyngeal,  and  from  the 
superficial  cardiac  nerve.  A filament,  called  the  inferior 
pharyngeal,  sometimes  proceeds  from  the  pneu mo-gastric  a 
little  below  the  other,  and  also  is  spent  upon  the  pharynx. 

The  pneumo-gastric,  at  the  place  where  it  detaches  these 
pharyngeal  branches,  or  a little  above  them,  becomes  soft- 
ened in  its  texture,  enlarges  somewhat,  and  has  the  fasciculi 
which  compose  it,  moderately  separated  by  a sort  of  red 
gelatinous  substance  interposed  between  them.  This  por- 
tion is  its  gangliform  plexus,  and  into  it  is  joined  one  or 
more  branches  from  the  accessory  nerve. 

The  Superior  Laryngeal  Nerve  Laryngeus  Su- 

perior) arises  from  the  gangliform  plexus.  It  descends  be- 
tween the  internal  carotid  and  the  superior  cervical  ganglion, 
anastomosing  on  the  way  with  the  latter,  with  the  pharyn- 
geal plexus,  and  the  hypo-glossal  nerve;  it  then  divides  into 
an  external  and  an  internal  laryngeal  branch.  The  former 
sends  its  filaments  to  the  muscles  situated  on  the  fore  part 
of  the  thyroid  cartilage;  to  the  thyroid  gland;  and  some  of 
them  penetrate  through  the  crico-thyroid  membrane  to  the 
lining  membrane  of  the  larynx.  The  internal  laryngeal 
branch  is  placed  above  the  other;  it  is  directed  towards  the 
thyreo-hyoid  membrane,  which  it  penetrates  and  then  begins 
to  ramify.  Some  of  the  branches  go  to  the  epiglottis  carti- 
lage, its  covering  membrane,  and  the  adjacent  portion  of 
the  lining  membrane  of  the  pharynx.  Other  branches  are 
distributed  to  the- small  muscles  which  move  the  arytenoid 
cartilages,  and  to  the  lining  membrane  of  the  larynx.  The 
filaments  which  go  to  the  epiglottis  have  an  arrangement 
indicated  by  Bichat;  that  of  going  into  the  foramina  which 
perforate  it,  but  they  cannot  be  traced  further. 

The  pneumo-gastric  afterwards  does  not  send  off  any  re- 
gular branches  till  it  reaches  the  lower  part  of  the  neck.  It 
then  detaches  two  or  three  filaments,  {rami  cardiaci)  which, 
on  the  right  side,  have  their  roots  about  an  inch  above  the 
subclavian  artery,  and  on  the  left  side,  an  inch  lower  down. 
On  the  right  side  they  descend  along  the  subclavian  and  the 
arteria  innominata,  on  the  left  along  the  left  carotid;  they 


PS£0MO-CrASTRIC  NERVE. 


477 


reach  the  arch  of  the  aorta,  and  in  their  course,  as  well  as 
there,  anastomose  very  freely  with  the  superficial  cardiac 
nerve.  The  rami  cardiaci  are  frequently  more  abundant  on 
the  right  side  than  on  the  left. 

The  Inferior  Laryngeal  Nerve  (Nervns  Laryngeus  In- 
ferior, Recurrens)  is  a considerable  branch  of  the  pneumo- 
gastric,  which  comes  oflf  next  to  the  cardiac.  On  the  right 
side  it  arises  immediately  after  the  trunk  has  passed  be- 
tween the  subclavian  artery  and  the  subclavian  vein.  It 
then  winds  around  the  subclavian  artery  so  as  to  retain  the 
latter  in  its  loop;  having  thus  got  behind  the  artery,  it  then 
ascends  towards  the  larynx  on  the  side  of  the  trachea,  co- 
vered by  the  common  carotid  and  by  the  inferior  laryngeal 
artery. 

In  this  course  the  inferior  laryngeal  nerve  detaches  the 
following  branches:  1.  From  the  convexity  of  its  loop  it 
sends  filaments  to  the  assistance  of  the  cardiac  branches  just 
spoken  of,  arising  from  the  pneumo-gastric,  and  to  those 
coming  from  the  inferior  cervical  ganglion  of  the  sympa- 
thetic. 2.  It  detaches  the  pulmonary  branches,  the  origin 
of  which  is  complicated  with  the  plexus  of  nerves  ex- 
isting about  their  roots;  these  descend  in  front  of  the  tra- 
chea, reach  the  pulmonary  artery,  and  follow  its  ramifica- 
tions into  the  lungs;  some  of  the  filaments,  however,  go  to 
the  cardiac  plexus.  3.  The  inferior  pharyngeal  then  sends 
many  filaments  to  the  oesophagus;  4.  Branches  which  go  to 
the  inferior  part  of  the  thyroid  gland;  5.  Filaments  to  the 
trachea,  some  of  which  penetrate  the  membrane  on  its 
posterior  part,  others  go  between  the  cartilages;  they  are 
then  distributed  to  the  lining  membrane  and  to  the  mucous 
glands  of  the  part.  6.  The  inferior  laryngeal  nerve  is  then 
distributed  in  branches  to  the  inferior  constrictor  of  the 
pharynx  and  its  lining  membrane;  but  the  most  of  its  ter- 
minating filaments  penetrate  to  the  larynx  between  the  thy- 
roid and  the  cricoid  cartilage,  and  are  lost  upon  the  lining 
membrane  of  the  larynx,  and  upon  the  small  muscles  which 
move  the  arytenoid  cartilages.  These  terminating  filaments 


47S 


NERVOUS  SYSTEM. 


anastomose  with  such  as  come  from  the  superior  laryngeal 
nerve. 

It  is  generally  stated  by  anatomists  that  the  distribution 
of  the  recurrent  laryngeal  nerve  to  the  lar)mx,  is  confined 
to  the  thyreo-arytenoid,  crico-arytenoid,  posterior  and  late- 
ral muscles.  Mr.  G.  Rainy,  states  in  the  London  Medical 
Gazette,  that  he  has  repeatedly  traced  its  filaments  also,  to 
the  transverse  and  oblique  arytenoid.*  The  recurrent  of 
the  left  side  forms  a much  larger  loop  than  the  other,  and 
arises  lower  down,  inasmuch  as  it  has  to  wind  around  the 
arch  of  the  aorta,  at  the  origin  of  the  left  subclavian  artery; 
with  some  inconsiderable  exceptions,  its  course  and  distri- 
bution afterwards  are  precisely  the  same  with  those  of  the 
nerve  of  the  right  side. 

B.  The  Thoracic  Branches  of  the  pneumo -gastric  are  as 
follow:  The  inferior  tracheal  nerves  come  from  it  just  be- 
low the  recurrent;  they  are  five  or  six  in  number;  some  of 
them  go  in  front  of  the  trachea  and  bronchia,  and  others 
behind  them.  They  are  complicated  by  anastomoses  with 
the  branches  of  the  recurrent  nerve,  and  with  those  of  the 
inferior  cervical  ganglion,  and  form  a small  plexus,  deno- 
minated the  anterior  pulmonary,  which  lies  upon  the  front 
of  the  root  of  the  lung,  and  has  its  filaments  following  the 
branches  of  the  pulmonary  artery  through  the  lung.  The 
posterior  filaments  supply  the  structure  of  the  bronchia  by 
penetrating  it,  and  some  of  them  go  to  join  the  posterior 
pulmonary  plexus. 

As  the  pneumo-gastric  gets  behind  the  trachea  and  the 
bronchia,  it  is  sensibly  enlarged  and  somewhat  flattened, 
the  cohesion  of  its  fasciculi  being  somewhat  looser.  Seve- 
ral filaments  depart  there  from  it,  which  form  an  intertex- 
ture with  each  other;  some  of  them  pass  inwards,  to  be  dis- 
tributed on  the  bronchia,  trachea,  and  oesophagus.  Others, 
which  are  given  off  as  the  nerve  lies  upon  the  posterior  face 
of  the  root  of  the  lung,  amounting  to  six  or  seven  in  nura- 

* Am.  Med.  Journal,  Vol.  iv.  p.  198 


PNEUMO-GASTRIC  NERVE. 


479 


ber,  but  being  of  various  sizes;  run  transversely  outwards, 
and  form  an  intertexture  with  one  another:  The  latter  are 
joined  by  filaments  from  the  inferior  cervical  and  the  first 
dorsal  ganglion  of  the  sympathetic,  and  thus  constitute  the 
posterior  pulmonary  plexus.  The  filaments  from  this  plexus 
follow  the  distribution  of  the  bronchia;  and  according  to  Bi- 
chat, are  all  destined  to  the  mucous  membrane  and  the  mu- 
cous glands  of  the  lung;  as  they  may  be  traced  piercing  suc- 
cessively the  ramifications  of  the  bronchia,  in  order  to  reach 
its  lining  membrane. 

On  the  right  side,  the  par  vagum,  while  furnishing  the 
pulmonary  plexus,  and  for  some  distance  lower  down,  is 
divided  into  from  four  to  six  considerable  fasciculi,  which 
form  with  each  other  a plexus  or  series  of  anastomoses 
having  very  large  meshes,  and  from  which  proceed  many 
filaments  to  the  oesophagus.  Afterwards  these  fasciculi  are 
assembled  into  a single  chord,  which  proceeds  on  the  pos- 
terior face  of  the  oesophagus,  along  with  it  into  the  ab- 
domen. 

^ On  the  left  side,  the  par  vagum,  after  forming  the  pos- 
terior pulmonary  plexus,  is  split  into  two  or  three  fasciculi; 
which  likewise  furnish  branches  to  the  oesophagus;  and 
unite  to  form  a single  chord,  which  proceeds  on  the  front 
surface  of  the  oesophagus,  along  with  it  into  the  abdomen. 

The  two  nerves  while  descending  in  this  way,  send  fre- 
quent anastomotic  filaments  to  each  otlier,  and  to  the  oeso- 
phagus. 

C.  In  the  Abdomen  the  par  vagum  is  distributed,  as  fol- 
lows: Filaments  are  sent  from  each,  which  form  a plex- 
us around  the  cardiac  orifice  of  the  stomach.  The  right 
nerve  is  then  divided  into  many  branches;  some  are  distri- 
buted on  the  posterior  face  of  the  stomach;  others  go  along 
the  lesser  curvature  of  this  viscus,  and  reach  thereby  the 
pylorus,  where  they  anastomose  with  filaments  from  the 
left  nerve,  and  from  the  gastric  plexus  of  the  sympathetic; 
others  go  behind  the  stomach  to  join  the  solar  plexus,  and 
are  blended  with  the  latter  in  its  distribution  to  the  liver, 


480 


NERVOUS  SYSTEM. 


vena  portarum,  duodeum,  and  pancreas.  The  left  par  va- 
gum  being  placed  in  front  of  the  cardia,  is  resolved  into 
several  radiating  filaments  or  fasciculi,  some  of  which  sup- 
ply the  anterior  face  of  the  stomach,  others  go  along  its 
lesser  curvature  to  the  pylorus,  to  anastomose  with  the 
right  nerve  and  the  gastric  branches  of  the  sympathetic, 
and  are  finally  blended,  after  the  same  manner  as  the  pre- 
ceding, with  the  solar  plexus. 


The  Sympathetic  Nerve  {Nervus  Sympatheticus  Mag- 
nus, Intercostalis  Maximus,  Gangliosus,)  in  a 

great  number  of  respects,  from  every  other  nerve  of  the 
body;  and,  if  we  were  actuated  only  by  its  peculiarities,  with 
Bichat,  Meckel,  and  others,  we  might  with  great  proprie- 
ty, set  it  apart  as  something  having  a claim  to  an  insulated 
description  and  location.  The  dissection  of  it,  however, 
is  so  much  blended  with  that  of  the  par  vagum,  that  the 
descriptions  of  the  two,  go  best  hand  in  hand;  and  are 
therefore  most  conveniently  studied  together. 

This  nerve  consists  in  a series  or  chain  of  ganglions,  ex- 
tending from  the  base  of  the  cranium  to  the  lower  end  of 
the  sacrum.  They  are  placed  on  the  lateral  part  of  the  bo- 
dies of  the  vertebrae,  are  united  to  each  other  by  interme- 
diate nervous  chords,  and  send  off  continually  filaments  to 
the  adjacent  organs.  With  the  exception  of  the  neck, 
there  is  a ganglion  for  each  intervertebral  space,  both  of  the 
true  vertebras  and  sacrum.  Besides  these  ganglions,  there 
are  others  which  are  situated  around  the  trunks  of  some  of 
the  large  vessels  of  the  abdomen. 

The  superior  extremity  of  the  sympathetic  nerve,  oppo- 


CHAPTER  II, 


OF  THE  SYMPATHETIC  NERVE.*' 


Anton.  Scarpa,  Tabul.  Neurolog’. 


THE  SYMPATHETIC  NERVE. 


481 


site  to  the  transverse  process  of  the  second  cervical  verte 
bra,  and  behind  the  internal  carotid  artery,  forms  a ganglion, 
which  for  the  purpose  of  description,  may  be  considered  as 
the  first  of  the  series.  This  ganglion  is  the  superior  cer- 
vical. The  nervus  motor  externus  oculi  in  passing  through 
the  cavernous  sinus,  and  the  vidian  nerve  in  passing  by  the 
point  of  the  petrous  bone,  both  send  a filament  downwards 
through  the  carotid  canal;  which  two  filaments  unite  to 
form  a single  chord,  that  runs  into  the  superior  extremity 
of  this  ganglion.  The  filament  from  the  vidian  nerve  is, 
as  mentioned,  the  deep  petrous  nerve.  The  common  view 
taken  by  anatomists  of  this  nervous  connexion  is,  that  it  is 
the  beginning  of  the  sympathetic,  though  by  Bichat  it  is  de- 
scribed as  the  termination,  or  one  of  its  extremities.  The 
distinction,  though  important  physiologically,  is  less  so 
when  the  object  is  simply  to  describe  the  course  and  anato- 
mical relations  of  this  nerve,  as  they  may  be  equally  under- 
stood by  either  mode  of  description. 

The  branch  from  the  motor  externus  most  frequenth’ 
forms,  on  the  external  face  of  the  internal  carotid,  in  the 
cavernous  sinus,  a ganglion,  {Ganglion  Cavernosum)  dis- 
covered by  Laumonier,  which  is  sometimes  made  by  seve- 
ral filaments  from  the  motor  externus  instead  of  one.  Mr. 
Lobstein,in  his  Essay  on  the  Sympathetic,  has  attributed  this 
ganglion  to  the  deep  petrous  nerve,  in  which  I think  he  is 
mistaken.  From  the  ganglion  cavernosum,  it  has,  of  late, 
been  ascertained  that  filaments  maybe  traced  to  the  Gangli- 
on of  Gasser,  {Plexus  Gangliformis,)  of  the  trigeminus,  to 
the  pituitary  gland,  to  the  infundibulum;  and,  moreover,  a 
fasciculus  which,  according  to  H.  Cloquet,  forms  a plexus 
around  the  ophthalmic  artery,  and  may  be  traced  along  all 
its  branches,  even  the  central  artery  of  the  retina.  This 
plexus  anastomoses  with  the  lenticular  ganglion,  and  con- 
sequently establishes  a direct  nervous  communication  be- 
tween the  sympathetic,  the  motor  oculi,  and  first  branch 
of  the  fifth  pair.  The  knowledge  of  this  connexion  has 
caused  anatomists  to  locate  the  lenticular  ganglion  and  the 
ciliary  nerves  in  the  ganglionic  system  of  the  sympathe- 
tic, as  forming  a part  of  the  latter. 

VoL.  II.-— 61 


WJiRVOUS  SyS'i’EM. 


Tlie  sympathetic,  in  descending  the  neck,  is  placed  behind 
the  carotid  artery  and  internal  jugular  vein.  It  is  commonly 
said  to  be  enclosed  in  the  sheath  of  these  great  vessels,  but 
tlie  statement  is  loose  and  inaccurate,  as  it  is  fastened  to  the 
front  surface  of  the  longus  colli  muscle  by  cellular  substance 
distinct  from  the  sheath,  as  may  be  manifested  by  pushing 
a knife  handle  between  them  and  raising  up  the  sheath.  The 
chord  which  comes  down  from  the  carotid  canal  is.  close 
to  the  pneu mo-gastric  and  hypoglossal  nerves.  Having 
formed  the  first  cervical  ganglion,  it  descends  as  mentioned; 
and,  opposite  to  the  space  between  the  fifth  and  the  sixth 
cervical  vertebra,  it  is  again  enlarged  into  the  Middle  Cer- 
vical Ganglion,  which  is  much  smaller  and  more  irregular 
than  the  first.  The  sympathetic  is  then  traced  with  some, 
difficulty,  in  consequence  of  the  numerous  branches  coming 
from  it;  but,  with  attention,  a trunk  may  be  found  as  the 
continuation  of  it.  This  trunk  passes  to  the  interval  between 
the  head  of  the  first  rib  and  the  transverse  process  of  the 
last  cervical  vertebra,  and  there  enlarges  into  another  gan- 
glion, called  Inferior  Cervical,  or  First  Dorsal. 

To  understand  well  the  connexions  of  the  sympathetic  in 
the  neck,  each  of  the  cervical  ganglions  must  be  studied 
particularly. 

1st.  The  Superior  Cervical  Ganglion  yvSe,?,  considera- 
bly in  its  extent;,  commencing  very  generally  opposite  to 
the  second  cervical  vertebra,  it  is  sometimes  elongated  to  the 
lower  part  of  the  third  and  even  of  the  fourth.  In  cases  of 
unusual  elongation,  it  is  smaller  than  in  others. 

It  sends  off,  from  its  external  margin,  several  filaments, 
about  four,  which  cross  the  anterior  face  of  the  rectus  anticus 
major  muscle,  and  terminate  by  anastomosing  with  the  ante- 
rior fasciculi  of  the  occipital  nerve  and  of  the  three  first  cervi- 
cal; when  the  ganglion  is  short,  the  two  lower  filaments  come 
from  the  sympathetic  below  it,  instead  of  from  the  ganglion. 

Several  filaments  also  proceed  from  this  ganglion  to  the 
contiguous  muscles  on  the  vertebral  column,  to  the  pharynx, 
to  the  larynx,  and  to  the  thyroid  gland. 


THE  SYMPATHETIC  NERVE. 


4S3 


This  ganglion  also  sends  off  what  are  called  its  i^nterior 
branches,  which  are  peculiar  for  their  reddish  colour  and 
for  their  softness;  the  latter  quality  has  obtained  for  them 
the  name  of  Nervi  Molles.  They  may  be  referred,  by  their 
position,  to  three  orders.  The  superior  ascend  to  anasto- 
mose with  the  pneu mo-gastric,  hypoglossal,  and  facial  nerves, 
near  their  exit  from  the  cranium.  The  middle  are  two  or 
three  in  number,  but  immediately  divide  into  many  filaments, 
forming  the  carotid  plexus  by  assistance  from  the  pneumo- 
gastric,  glosso-pharyngeal,  and  facial  nerves.  Some  of  the 
branches  of  this  plexus  descend  behind  the  primitive  caro- 
tid, at  the  place  of  its  bifurcation,  and  accompany  it  to  its 
origin,  continually  interlacing  with  each  other.  Others  sur- 
round, after  the  same  manner,  the  external  carotid,  and  sub- 
divide into  a plexus  for  each  of  its  branches,  so  that  very 
fine  filaments  may  be  traced  along  the  superior  thyroidal, 
the  lingual,  facial,  occipital,  and  temporal  arteries.  These 
nerves  are,  for  the  most  part,  difficult  to  trace,  from  their 
extreme  tenuity.  The  primitive  branches,  from  w'hich  these 
plexuses  come,  are  sometimes  previously  united  into  a small 
ganglion,  which  serves  as  a common  centre  to  all  these  ner- 
vous irradiations.  The  third  order  of  anterior  branches, 
amounting  to  from  four  to  six,  come  either  from  the  gan- 
glion or  from  the  sympathetic  just  below  it.  The  chord 
formed  by  their  union,  called  the  Superficial  Cardiac  Nerve, 
descends  on  the  external  side  of  the  primitive  carotid,  anas- 
tomosing with  filaments  from  the  pneumo-gastric  and  from 
the  descendens  noni.  It  gives  small  ramifications  to  the  con- 
tiguous parts,  as  to  the  pharynx,  oesophagus,  the  sterno-hy- 
oid  and  thyroid  muscles.  It  terminates  in  the  lower  part 
of  the  neck,  by  detacffiing  anastomosing  branches  to  the 
branches  of  the  recurrent  nerve;  some  of  them  also  go  along 
the  inferior  thyroid  artery  to  the  thyroid  gland.  What  re- 
mains of  it  is  lost  in  the  middle  cardiac  nerve,  for  it  can- 
not be  traced,  in  an  insulated  and  distinct  manner,  to  the 
heart;  from  which  cause,  its  appellation  is  objectionable. 

2.  The  Middle  Cervical  Ganglion,  placed  intermediate- 


^"ERVOUS  SYSTEM. 


IS4 

ly  to  the  fifth  and  sixth  cervical  vertebra,  upon  the  longus 
colli  muscle,  is  there  concealed  by  the  common  carotid,  the 
internal  jugul  r vein,  and  the  pneumo-gastric  nerve.  It  is 
sometimes  deficient:  according  to  Meckel,  in  the  proportion 
of  once  in  three  times.  In  my  own  dissections  I have  al- 
ways found  it,  though  under  various  circumstances  of  size 
and  form.  It  is  more  flattened  than  the  preceding,  and  ne- 
ver so  long.  Sometimes  it  is  double.  Like  the  preceding, 
it  has  a great  many  filaments  attached  to,  or  emanating 
from  it. 

The  externa]  filaments,  amounting  to  about  three  in  num- 
ber, pass  from  it  to  the  anterior  fasciculi  of  the  fourth,  fifth, 
and  sixth  cervical  nerves,  between  the  origins  of  the  sca- 
leni  muscles.  Some  of  its  filaments  accompany  the  infe- 
rior thyroid  artery,  and,  along  with  the  superficial  car- 
diac, form  a plexus  around  it,  which  reaches  to  the  thyroid 
gland. 

The  Middle  Cardiac  Nerve  is  formed  by  several  of  the 
anterior  branches,  collecting  into  a single  chord.  The  lat- 
ter descends  along  the  external  side  of  the  primitive  caro- 
tid, crosses,  on  the  right  side  of  the  body,  the  root  of  the 
subclavian  arteiy,  and  then,  going  along  the  posterior  face 
of  the  arteria  innominata,  it  gets  between  the  aorta  and  the 
bifurcation  of  the  trachea,  where  it  is  merged  in  the  com- 
mencement of  the  cadiac  plexus  of  nerves.  On  the  left  side, 
the  middle  cardiac  nerve  is  formed  by  an  assemblage  of  fila- 
ments from  the  middle  and  inferior  cervical  ganglions,  which 
descend  along  the  left  subclavian  artery  to  the  aorta,  and  are 
joined,  on  the  front  of  the  latter,  by  the  superficial  cardiac 
nerve.  On  both  sides,  these  cardiac  nerves  form  intricate 
anastomoses  with  the  pneumo-gastric  nerve  and  its  recurrent 
branch. 

3.  The  Inferior  Cervical  Ganglion^  situated  as  men- 
tioned, near  the  head  of  the  first  rib,  like  the  others,  is  sub- 
ject to  variations  in  its  form  and  size.  Several  filaments 
may  be  traced  between  it  and  the  middle  cervical  ganglion. 
One  penetrates  into  the  canal  of  the  transverse  processes 


THE  SYMPATHETIC  NERVE. 


4ti5 

along  with  the  vertebral  artery,  and,  forming  a plexus 
around  it,  may  be  traced  distributing  branches  to  the  heads 
of  the  contiguous  muscles,  as  high  up  as  the  second  cervi- 
cal vertebra. 

The  external  branches  of  the  inferior  cervical  ganglion 
are  numerous  and  small.  Some  of  them  anastomose  with 
the  anterior  fasciculi  of  the  two  or  three  inferior  cervical 
and  the  first  dorsal  nerve.  Others  form  a plexus  around 
the  subclavian  artery,  and  follow  the  latter,  in  its  distribu- 
tion, to  tbe  upper  extremity  and  to  the  shoulder. 

The  anterior  branches  of  this  ganglion  concur,  after  some 
anastomoses  with  each  other,  to  form  a single  chord,  the  In- 
ferior Cardiac  Nerve,  which  goes,  on  the  right  side,  along 
the  arteria  innominata,  to  be  blended  with  the  cardiac 
plexus.  On  the  left  side,  it  is  not  so  distinct,  but  is  blend- 
ed with  the  middle  cardiac  nerve,  and  forms  its  inferior  root. 


Of  the  Cardiac  Plexus  of  the  Sympathetic. 

The  Cardiac  Plexus  [Plexus  Cardiacus)  is  situated  be- 
tween the  arch  of  the  aorta,  and  the  lower  part  of  the  tra- 
chea and  the  bronchiae,  and  extends  from  the  division  of 
the  pulmonary  artery  to  the  commencement  of  the  arteria 
innominata.  It  is  formed  almost  wholly  from  the  branches 
sent  by  the  three  cervical  ganglions  of  the  sympathetic,  and 
principally  from  that  of  the  middle  one,  or  the  middle  car- 
diac nerve.  The  filaments  which  come  from  the  recurrent 
nerve  and  the  par  vagum  are  blended  into  the  cardiac  plexus 
in  such  a manner  that  they  cannot  be  traced  immediately  to 
the  heart.  It  is  worthy  of  remark,  that  the  three  cardiac 
nerves  of  the  right  side  are  more  constantly  found  than 
the  same  number  on  the  left,  in  consequence  of  the  lower 
one  of  the  latter  soon  merging  itself,  after  its  origin,  into 
the  middle  cardiac  nerve  of  that  side. 

The  cardiac  plexus  is  formed  by  the  common  assemblage 
of  the  nerves  from  the  two  sides  of  the  neck,  and  is  there- 
fore single.  From  this  plexus  arise  all  the  nerves  which 
go  to  the  heart,  so  that  in  tracing  them  the  distinction  be- 


NERVOUS  SYSTEM. 


48() 

tween  right  and  left  is  confounded.  Scarpa  has  pointed  out, 
in  this  circumstance,  an  analogy  between  them  and  the 
nerves  which  supply  the  abdominal  viscera. 

The  cardiac  plexus  is  distinguished  by  the  softness  of  its 
texture.  For  the  purpose  of  description,  its  brapches  may 
be  divided  into  Anterior,  Posterior,  and  Inferior. 

The  Anterior  Branches  are  but  few.  They  are  found 
on  the  front  of  the  arch  of  the  aorta.  One  of  them  crosses 
it  on  the  right  side  of  the  arteria  innominata;  others  cross  it 
from  the  root  of  the  left  carotid  and  subclavian  downwards. 
In  both  cases,  several  of  the  terminating  filaments  run  into 
the  anterior  coronary  plexus.* 

The  Posterior  Branches  are  more  numerous,  but  run 
only  a short  course,  when  they  are  merged  in  the  anterior 
pulmonary  plexus  formed  by  the  par  vagum. 

The  Inferior  Branches  are  the  largest  and  the  most  abun- 
dant. Some  of  them  follow  the  pulmonary  artery  until  its 
entrance  into  the  lungs,  others  are  distributed  upon  the  pul- 
monary veins,  but  the  greater  number  of  them  are  arranged 
into  two  plexuses  called  Coronary,  from  their  observing  the 
course  of  the  coronary  arteries.  The  posterior  coronary 
plexus  is  larger  than  the  other.  It  reaches  the  base  of  the 
heart,  along  the  left  pulmonary  artery,  and  has  its  filaments 
distributed  principally  to  the  left  auricle  and  the  left  ventri- 
cle, observing  the  course  of  the  left  coronary  artery  and  of 
its  branches.  The  anterior  coronary  plexus  gets  in  front  of 
the  heart,  between  the  aorta  and  the  pulmonary  artery.  It 
anastomoses  freely  at  its  superior  part  with  the  other,  and 
is  then  distributed  to  the  right  auricle  and  ventricle,  along 
the  course  of  the  right  coronary  artery  and  of  its  branches. 

Of  the  Thoracic  Ganglions  of  the  Sympathetic. 

These  ganglions  are  twelve  in  number,  and  are  placed  on 
or  near  the  heads  of  the  ribs,  at  the  commencement  of  each 
intercostal  space,  and  are  only  covered  by  the  pleura. 


Scarpa. 


THE  SYMPATHETIC  NERVE. 


487 


Their  shape  is  irregular,  and  they  differ  also  in  size,  being 
always  smaller  than  the  cervical  ganglions.  The  chord  of 
the  sympathetic  is  continued  successively  from  one  ganglion 
to  another,  so  that  they  form  a complete  chain  by  their  con- 
nexion with  each  other. 

From  each  ganglion  there  proceeds  one  or  more  exter- 
nal branches,  which  go  outwards  to  anastomose  with  the  in- 
tercostal nerve  of  the  corresponding  part.  Each  ganglion 
also  detaches  one  or  more  internal  branches  or  filaments 
to  the  adjacent  parts  lying  on  the  vertebral  column:  some 
go  to  the  cellular  substance,  others  to  the  longus  colli  mus- 
cle, others  to  the  aorta,  others  to  the  cardiac  and  to  the  pul- 
monary plexuses.  Among  these  internal  branches  there 
are  several  which  concur  to  form  the  Splanchnic  Nerves,  of 
which  there  are  two:  the  Great  and  the  Small. 

The  Great  Splanchnic  Nerve  arises,  by  filaments,  from 
the  sixth  to  the  ninth  or  tenth  thoracic  ganglions  inclusive- 
ly; one  or  more  filaments  coming  from  each  ganglion.  They 
are  directed  downwards  and  forwards  on  the  sides  of  the 
dorsal  vertebrae,  covered  by  the  pleura,  and  unite  succes- 
sively into  a trunk  about  the  eleventh  dorsal  vertebra. 
This  trunk  penetrates  into  the  cavity  of  the  abdomen,  be- 
tween the  middle  and  the  internal  head  of  the  lesser  mus- 
cle of  the  diaphragm,  and  sometimes  by  the  opening  for  the 
aorta. 

Having  got  into  the  abdomen,  the  great  splanchnic  di- 
vides into  several  fasciculi,  which,  diverging  from  each 
other,  are  concealed  on  the  right  side  by  the  liver  and  on 
the  left  by  the  stomach.  On  each  side  of  the  aorta,  there 
is  a large  ganglion  formed  by  an  assemblage  of  several 
smaller  ones;  it  is  called  the  Semilunar.  Into  it  terminate, 
for  the  most  part,  these  fasciculi;  some  of  them,  however, 
go  immediately  into  the  solar  plexus,  which  emanates  from 
the  semilunar  ganglion. 

The  Small  Splanchnic  Nerve  is  derived,  by  filaments, 
from  the  tenth  and  the  eleventh  thoracic  ganglions.  Having 


488 


NERVOUS  SYSTEM. 


united,  they  penetrate  the  crus  of  the  diaphragm,  and  reach- 
ing the  abdomen,  the  trunk  is  divided  into  two  branches,  of 
which  the  uppermost  ascends  to  join  the  great  splanchnic 
before  its  division,  and  the  lower  descends  to  join  the  re- 
nal plexus. 

Besides  these  two  splanchnic  nerves,  it  frequently  hap- 
pens that  there  are  others  which  come  from  the  eleventh 
and  twelfth  thoracic  ganglions,  and  from  the  communicating 
branch  between  the  last  thoracic  and  the  first  lumbar.  They 
unite  into  a trunk  which  goes  to  the  renal  plexus,  and  have 
been  called,  by  Walter,  the  Posterior  Renal  Nerves. 


Of  the  Solar  Plexus. 

The  Semilunar  Ganglion,  situated,  as  mentioned,  on  the 
side  of  the  aorta,  is  somewhat  semicircular  or  oval,  and  is 
about  an  inch  long;  its  form,  however,  is  much  diversified 
in  different  subjects.  The  several  ganglions  of  which  it  is 
composed,  are  frequently  fused  into  a single  one.  That  of 
the  right  side  is  more  voluminous  than  the  other,  and  is 
placed  between  the  ascending  vena  cava  and  the  crus  of  the 
diaphragm,  somewhat  above  the  right  renal  artery.  That 
of  the  left  is  situated  upon  the  left  crus  of  the  diaphragm, 
somewhat  below  the  splenic  artery.  Between  their  infe- 
rior extremities,  there  are  generally  two  or  three  smaller 
ganglions. 

These  several  ganglions  are  united  by  numerous  fila- 
ments, which  send  out  many  ramifications  and  anastomose 
freely  with  each  other. 

The  preceding  arrangement  may  be  considered  as  the  root 
of  the  solar  plexus,  which  extends  from  the  coeliac  artery 
to  the  lower  margin  of  the  emulgents,  and  as  it  is  common 
to  the  ganglions  of  the  two  sides,  it  is  an  inch  and  a half 
or  two  inches  wide.  Bichat  has  very  properly  remarked, 
that  this  plexus  seems  to  exist  for  the  aorta,  as  all  the  di- 
visions which  it  sends  out  follow  so  exactly  the  branches  of 
this  artery,  that  we  are  forced  to  adopt  the  latter  as  the  ba- 
sis of  the  description.  The  intertexture  and  the  number 


THE  SYMPATHETIC  NERVE. 


489 


of  the  branches  emanating  from  the  solar  plexus  are  so  com- 
plicated, “that  a description  of  individual  branches  would 
be  almost  endless,  as  well  as  unintelligible;  anatomists  are, 
therefore,  generally  agreed  to  describe  the  plexus  accord- 
ing to  the  order  of  the  arteries  which  its  detachments  ad- 
here to  and  surround. 

1.  The  Diaphragmatic  Plexus  consists  of  a few  fila- 
ments coming  from  the  superior  part  of  the  solar,  and  fol- 
lowing the  course  of  the  phrenic  arteries.  Some  of  them 
anastomose  with  the  terminating  filaments  of  the  phrenic 
nerve,  in  the  thickness  of  the  diaphragm. 

2.  The  Plexus  which  surrounds  the  C celiac  tdr ter y ,\\kc, 
it,  is  quickly  disposed  into  three  divisions,  which  follow  the 
branches  of  this  artery. 

a.  The  Superior  Coronary  Plexus  of  the  stomach,  is 
the  smallest  of  the  three.  It  attends  the  corresponding  ar- 
tery along  the  lesser  curvature  of  the  stomach  to  the  py- 
lorus, supplying  the  stomach  continually  with  very  fine  fila- 
ments. In  its  course,  it  anastomoses  with  the  par  vagura, 
and  sends  filaments  to  the  hepatic  plexus. 

b.  The  Hepatic  Plexus  is  the  largest  of  the  three.  It 
surrounds  the  hepatic  artery  and  the  vena  portarum,  and  in 
its  course  detaches  branches  which  go  with  the  right  gastro- 
epiploic artery  to  the  great  curvature  of  the  stomach,  and 
constitute  the  inferior  coronary  plexus.  Branches  are  also 
sent  to  the  pancreas  and  to  the  duodenum.  The  hepatic 
plexus  then  enters  the  transverse  fissure  of  the  liver,  and 
its  branches  may  be  traced  to  the  several  lobes  and  to  the 
gall-bladder. 

c.  The  Splenic  Plexus  is  but  small,  and  surrounds  the 
splenic  artery.  The  few  branches  of  which  it  is  composed, 
anastomose  but  rarely  with  each  other.  Some  of  them  are 
distributed  upon  the  pancreas,  along  with  the  pancreatic 

VoL.  II. — 62 


490 


NERVOUS  SYSTEM. 


branches  of  the  splenic  artery;  others  go  with  the  left  gas- 
tro-epiploic  artery  to  the  left  extremity  and  to  the  greater 
curvature  of  the  stomach;  the  remainder  penetrate  into 
the  substance  of  the  spleen,  through  its  fissure,  along  with 
the  branches  of  the  splenic  artery. 

3.  The  Supei'ior  Mesenteric  Plexus  is  derived  from  the 
solar,  near  the  superior  mesenteric  artery;  it  descends  some 
short  distance  on  the  aorta,  before  it  reaches  the  latter.  It 
descends  with  the  artery  between  the  pancreas  and  the  duo- 
denum, and  is  then  included  between  the  two  laminae  of 
mesentery;  it  is  then  distributed,  by  very  numerous  fila- 
ments, along  with  the  branches  of  the  artery,  to  the  whole 
of  the  small  intestines,  to  the  coecum,  and  to  the  ascending 
and  transverse  colon. 

4.  The  Renal  Plexus,  one  on  each  side,  is  derived  from 
the  lower  lateral  part  of  the  solar.  Two  or  three  gan- 
glions, on  the  root  of  the  renal  artery,  contribute  to  it,  and  it 
is  also  re-enforced  by  an  addition  from  the  lesser  splanchnic 
nerve.  The  branches  which  form  this  plexus  do  not  anas- 
tomose much,  till  they  get  near  the  kidney;  they  tlien  pe- 
netrate into  its  substance,  through  the  fissure.  Some  fila- 
ments from  this  plexus  go  to  the  capsulae  renales:  others 
follow  the  course  of  the  spermatic  artery,  and  constitute  the 
spermatic  plexus  which  goes  to  the  testicle  in  the  male,  and 
to  the  ovarium  in  the  female. 

5.  The  Inferior  Mesenteric  Plexus  is  a continuation  of 
the  solar,  on  the  anterior  face  of  the  abdominal  aorta.  It  is 
much  smaller  than  the  superior  mesenteric  plexus,  though 
it  receives  continually,  in  its  descent,  filaments  from  the 
lumbar  ganglions  of  the  sympathetic.  It  forms  frequent 
anastomoses  around  the  root  of  the  inferior  mesenteric  ar- 
tery and  near  the  superior  strait  of  the  pelvis,  is  resolved 
into  two  columns  of  fibres.  One  column  is  distributed  along 
with  the  artery  to  the  rectum,  to  the  sigmoid  flexure  of  the 
colon,  and  to  the  left  section  of  the  latter,  thereby  anasto- 


THE  SYMPATHETIC  NERVE. 


491 


mosing  with  the  colic  branches  of  the  superior  mesenteric 
plexus.  The  other  column  descends  into  the  pelvis  in  front 
of  the  sacrum,  and  contributes  to  form  the  hypogastric 
plexus,  but  several  of  its  branches  also  follow  the  external 
and  the  internal  iliac  arteries. 

Of  the  Lumbar  Ganglions  of  the  Sympathetic. 

These  ganglions  are  five  in  number,  on  either  side,  and 
are  placed  anteriorly  on  the  sides  of  the  bodies  of  the  lum- 
bar vertebr®,  near  the  anterior  margin  of  the  psoas  magnus 
muscle.  Their  form  is  irregular;  they  are  smaller  than  the 
cervical  ganglions,  but  larger  than  the  dorsal. 

The  last  thoracic  ganglion  is  united  to  the  first  lumbar  by 
a small  branch,  which  may  be  considered  as  the  continuation 
of  the  sympathetic.  A deficiency  of  this  branch  has,  how- 
ever, been  several  times  observed  by  anatomists;  also  a de- 
ficiency in  the  connecting  nervous  chord  of  the  ganglions 
below.  The  ganglions  themselves  are  inconstant  in  their 
number,  being  sometimes  less  than  five;  they  vary  like- 
wise in  their  situation.  It  is  to  be  understood,  however, 
that  in  a majority  of  subjects,  the  sympathetic  goes  on  un- 
interruptedly from  one  ganglion  to  another,  sometimes  by 
one  branch,  on  other  occasions  by  two  or  three. 

Each  lumbar  ganglion  sends  outwards  one,  or  more  exter- 
nal branches,  which  applying  themselves  to  the  body  of  the 
contiguous  vertebra,  reach  the  corresponding  intervertebral 
foramen  of  the  loins,  and  join  with  the  anterior  branch  of 
the  corresponding  lumbar  nerve.  Some  of  these  external 
branches  are  spent  upon  the  quadratus  lumboi'um  muscle. 

Each  lumbar  ganglion,  or  the  intermediate  chord  of  the 
sympathetic,  also  detaches  branches  internally,  which  are 
very  small,  and  more  or  less  interwoven  with  each  other. 
These  branches  get  to  the  abdominal  aorta,  and,  joining  the 
inferior  mesenteric  plexus  upon  it,  are  distributed  along  with 
the  latter. 


192 


NERVOUS  SYSTEM- 


Of  the  Sacral  Ganglions  of  the  Sympathetic. 

There  are  generally  three  of  these  ganglions  which  may 
be  readily  found:  sometimes  four  or  five.  They  are  situa- 
ted in  a line,  on  the  anterior  face  of  the  sacrum,  near  the 
corresponding  foramina  for  the  transmission  of  the  sacral 
nerves;  and  are  united  with  each  other  by  intermediate 
fibres,  from  one  to  three  in  number,  which  are  the  continu- 
ation of  the  sympathetic  nerve.  Bichat  asserts,  that  fre- 
quently the  first  of  these  ganglions  is  not  united  to  the  last 
of  the  lumbar  by  an  intermediate  nerve,  so  that  there  the 
the  continuity  of  the  sympathetic  is  interrupted. 

Each  ganglion  sends  off,  externally,  one  or  more  fila- 
ments, by  which  it  is  united  to  the  corresponding  sacral 
nerve:  it  also  detaches  filaments  in  this  direction  to  the  py- 
riformis  and  the  levator  ani  muscles. 

Each  ganglion  likewise  detaches,  from  its  internal  mar- 
gin, ramifications,  which  go  obliquely  downwards  on  the 
front  of  the  sacrum,  and  anastomose  with  corresponding 
filaments  from  the  opposite  side. 

From  these  ganglions  many  branches  pass  forwards  to 
the  hypogastric  plexus;  which  is  formed  by  them,  by  the 
inferior  mesenteric  plexus,  and  by  a great  many  filaments 
from  the  lower  sacral  nerves,  principally  the  third.  This 
plexus  is  distributed  upon  the  rectum,  the  bladder,  vesicu- 
Ije  seminales,  and  prostate  of  the  male,  and,  in  place  of  the 
two  latter  in  the  female,  upon  the  vagina  and  the  uterus. 

The  last  sacral  ganglion  detaches  downwards  one  or  more 
filaments,  which  lie  upon  the  front  of  the  os  coccygis,  and 
anastomose  with  the  corresponding  filaments  from  the  other 
side,  to  form  a sort  of  arch,  the  convexity  of  which  is 
downwards.  In  this  manner,  terminates  the  chord  of  the 
sympathetic  nerve. 


trpPER  NINE  SPINAL  NERVES. 


493 


CHAPTER  III. 

OF  THE  NERVES  OF  THE  MEDULLA  SPINALIS. 

The  nerves  of  the  medulla  spinalis,  with  the  exception 
of  the  first,  which  from  its  position,  is  generally  called  the 
Sub-occipital  by  anatomists,  are  arranged  into  cervical,  dor- 
sal, lumbar,  and  sacral,  according  to  the  order  of  the  inter- 
vertebral foramina,  through  which  they  pass  out:  but  a 
much  better  division  would  be  Cervical,^  Thoracic,  and 
Abdominal.  Their  mode  of  origin  has  been  pointed  out  in 
the  account  of  the  medulla  spinalis,  as  well  as  the  ganglions 
formed  by  them. 


SECT.  I. — or  THE  UPPER  NINE  SPINAL  NERVES. 

These  are  spent  upon  the  neck,  upon  the  upper  extremi- 
ties, and  upon  the  diaphragm.  They  consist  in  the  Sub- 
occipital  Nerve,  the  Cervical,  and  the  First  Dorsal 

Of  the  Sub-occipital  Nerve. 

The  Sub- occipital  Nerve  {Nervus  Infra-occipitalis,  de- 
cimus  cerebri)  is  one  of  the  smallest  that  proceeds  frorn 
the  medulla  spinalis.  It  has  the  peculiarity,  generally,  of 
arising  by  a single  root  which  comes  from  the  anterior 
chord  of  the  medulla  spinalis,  between  the  occiput  and  the 
first  cervical  vertebra.  This  root  consists  of  from  two  to 
six  or  seven  fasciculi,  situated  one  above  another.  When 
the  posterior  root  exists,  it  is  very  small,  is  composed  of 
from  one  to  three  fasciculi,  and  anastomoses  with  the  acces- 
sory nerve. 

The  trunk  of  this  nerve  passes  from  the  vertebral  cavity 
through  the  foramen  formed  in  the  dura  mater  by  the  ver- 


In  this  case,  the  term  Ceivical  vould  include  the  first  eig'ht. 


494 


NERVOUS  SYSTEM. 


tebral  artery;  it  goes  out  below  tbe  latter,  and  between  the 
occiput  and  the  first  vertebra,  behind  its  superior  oblique 
process.  It  there  forms  a small  long  ganglion,  like  the 
other  spinal  nerves,  and  then  divides  into  an  anterior  and  a 
posterior  fasciculus. 

The  anterior  fasciculus  is  the  smaller  of  the  two;  it  fol- 
lows, in  some  measure,  the  course  of  the  vertebral  artery, 
and  going  forwards  to  the  front  of  the  transverse  process, 
is  then  divided  into  several  fine  filaments,  some  of  which 
go  to  the  contiguous  muscles  on  the  front  of  the  vertebrae; 
others  join  themselves  to  the  pneumo-gastric  and  hypo- 
glossal nerves,  and  to  the  superior  cervical  ganglion  of  the 
sympathetic;  others  anastomose  with  the  first  cervical 
nerve. 

The  posterior  fasciculus  runs  backwards,  and  is  distri- 
buted to  the  recti  and  the  obliquui  muscles  on  the  back  of 
the  neck,  and  to  the  complexus. 


Of  the  Cervical  Nerves. 

These  are  seven  in  number;  the  first  one  gets  from  the 
spinal  cavity  between  the  atlas  and  the  dentata,  and  the  last 
between  the  seventh  cervical  and  the  first  dorsal  vertebra. 
After  the  ganglion  is  formed  upon  the  posterior  fasciculus 
of  each,  the  trunk  made  by  the  union  of  the  two  fasciculi, 
divides  almost  immediately  again  into  an  anterior  and  a pos- 
terior trunk. 

Of  the  First  Cervical  Nerve. 

The  posterior  trunk  is  the  largest,  aTid  goes  directly  back- 
wards. It  has  its  filaments  distributed  to  many  of  the  mus- 
cles on  the  upper  posterior  part  of  the  cervical  vertebrje, 
and  to  the  integuments  of  the  part.  Some  of  the  branches 
ascend  through  the  muscles,  near  the  occiput;  and,  rising 
up  on  the  latter,  are  distributed  upon  its  integuments,  and 
upon  the  occipito-frontalis  muscle. 

The  anterior  trunk  is  directed  forwards  under  the  inferior 


UPPER  NINE  SPINAL  NERVES. 


495 


oblique  muscle  of  the  neck,  and  then  divides  into  two 
branches,  the  superior  joins  the  anterior  branch  of  the  sub- 
occipital  nerve,  and  anastomoses  with  the  first  cervical  gan- 
glion of  the  sympathetic,  and  with  the  par  vagum  and  the 
hypoglossal  nerve;  the  inferior  joins  the  anterior  branch  of 
the  second  cervical  nerve. 

Of  the  Second  Cervical  Nerve. 

This  nerve  issues  between  the  second  and  the  thii'd  cer- 
vical vertebra.  Its  posterior  trunk  is  spent  upon  the  trape- 
zius, complexus,  and  other  muscles  on  the  back  of  the  neck, 
and  upon  the  integuments  of  the  latter;  it  also  anastomoses 
with  the  posterior  trunk  of  the  nerve  above  and  below. 

The  anterior  branch  or  trunk  detaches,  first  of  all,  some 
small  filaments  to  the  muscles  on  the  front  of  the  cervical 
vertebrse;  it  then  divides  into  two  principal  fasciculi,  one  of 
which  ascends  and  the  other  descends. 

The  ascending  branch  goes  upwards  and  backwards,  and 
early  in  its  course  anastomoses  with  the  first  cervical  nerve, 
thereby  forming  with  it  a nervous  noose;  it  then  mounts 
upon  the  occiput,  and  is  distributed  upon  the  parts  on  the 
latter  region,  anterior  to  the  occipital  branches  of  the  pre- 
ceding nerve. 

The  descending  branch  turns  over  the  posterior  margin  of 
the  sterno-cleido  mastoideus  muscle,  and  gives  filaments  to 
it.  It  is  distributed  afterwards  by  branches,  some  of  which 
go  to  the  integuments  of  the  middle  and  inferior  parts  of  the 
neck,  {nervi  subcutanei  colli  medii  et  inferior es ;)  others 
go  to  the  integuments  of  the  neck  upon  the  angle  and  the 
base  of  the  lower  jaw,  {nervi  subcutanei  superiores;)  and 
one  to  the  external  ear,  {nervus  auricularus  cervicalis.) 

From  the  anterior  fasciculus  of  the  second  cervical  nerve, 
there  proceeds  a filament  downwards,  which  is  the  upper 
root  of  the  phrenic  nerve;  another  filament  from  it  joins  the 
superior  cervical  ganglion  of  the  sympathetic. 


NERVOUS  SYSTEM. 


4yti 


Of  the  Third  Cervical  Nerve. 

This  nerve  comes  out  between  the  third  and  the  fourth 
cervical  vertebra.  Its  posterior  fasciculus  is  distributed  to 
the  muscles  on  the  back  of  the  cervical  vertebrae,  and  to  the 
integuments  of  the  part;  anastomosing,  by  its  branches,  with 
the  nerve  above  and  below. 

The  anterior  fasciculus  is  larger  than  the  posterior,  and 
goes  obliquely  downwards  and  outwards  at  first;  it  sends 
anastomotic  branches  to  the  nerve  above  and  below;  it  also 
anastomoses  with  the  superior  cervical  ganglion  of  the  sym- 
pathetic and  with  the  descendens  noni.  One  of  its  branches, 
being  joined  by  the  branch  Just  spoken  of,  from  the  second 
cervical  nerve,  constitutes  the  root  of  the  phrenic  nerve.  But 
the  principal  number  of  its  branches  are  distributed  to  the 
integuments  along  the  clavicle,  {nervi  supra  clavicular es,) 
the  upper  part  of  the  sternum,  and  the  shoulder,  some  of 
them  going  into  the  contiguous  muscles,  as  the  trapezius, 
subclavius,  &c.  Several  anastomoses  exist  between  the 
branches  of  this  nerve  and  the  terminating  branches  of  the 
nervus  accessorius. 

The  three  preceding  cervical  nerves  form,  by  their  anas- 
tomoses with  each  other,  a plexus,  consisting  in  a number 
of  large  loops  or  arches,  which  lie  upon  the  sides  of  the  mus- 
cles connected  with  the  transverse  processes  of  the  cervical 
■^rtebrse.  There  are  commonly  two  series  of  anastomoses, 
the  branches  of  the  anterior  one  form  the  second  series,  and 
from  the  latter  proceeds,  for  the  most  part,  the  several 
branches  which  have  been  described.  These  anastomoses 
are  covered  by  the  upper  half  of  the  sterno-cleido  mastoid 
muscle,  are  involved  in  the  cellular  membrane  surrounding 
the  great  vessels  of  the  neck,  and  are  covered  by  the  lym- 
phatic glands.  Their  intertexture  and  distribution  are  such, 
that  no  adequate  idea  of  them  can  be  conveyed  without  dis- 
section. From  this  plexus  several  branches  go  to  the  ster- 
no-mastoid  muscle,  and  it  is  united  above  to  the  sub-occipital 
nerve  and  below  to  the  fourth  cervical. 


UPPER  NINE  SPINAL  NERVES. 


4P7 


Of  the  Phrenic  Nerve. 

The  Phrenic  Nerve  {Nervus  Phrenicus,  Diaphragma- 
ticus)  arises,  in  the  manner  stated  above,  from  the  anterior 
fasciculus  of  the  second  and  of  the  third  cervical,  and  is  as- 
sisted generally  by  two  or  three  filaments  from  the  upper 
part  of  the  brachial  plexus.  It  descends  vertically  on  the 
humeral  side  of  the  internal  jugular  vein,  but  removed  a 
considerable  distance  from  it,  and  is  attached,  by  cellular 
substance,  to  the  front  of  the  scalenus  anticus  muscle. 
Getting,  in  its  descent,  to  the  internal  margin  of  the  latter, 
it  passes  into  the  thorax,  at  the  inner  margin  of  the  first  rib, 
between  the  subclavian  artery,  and  the  subclavian  vein,  the 
latter  being  before  it.  It  then  goes  along  the  superior  me- 
diastinum to  the  pericardium,  to  the  side  of  which  it  ad- 
heres in  front  of  the  root  of  the  lung,  being  between  the 
pericardium  and  the  corresponding  portion  of  the  pleura; 
it  finally  reaches  the  diaphragm,  to  which  it  is  distributed. 

Just  before  the  phrenic  nerve  reaches  the  diaphragm,  it 
radiates  into  several  branches,  which  interchange  filaments. 
Some  of  the  branches  are  distributed  to  the  convex  surface 
of  the  diaphragm ; others,  penetrate  the  muscle,  and  are  dis- 
tributed in  its  thickness  and  upon  its  concave  surface.  On 
the  right  side  some  of  these  branches  pass  through  the  open- 
ing for  the  ascending  vena  cava,  and  thus  getting  into  the 
abdomen,  anastomose  with  the  solar  plexus,  and  with  the 
pneumo-gastric  nerve. 

The  phrenic  nerve  of  the  left  side  is  nearer  to  the  root  of 
the  lung  than  that  of  the  right,  in  consequence  of  the  pro- 
jection of  the  apex  of  the  heart  on  that  side.  Its  distribu- 
tion in  other  respects  does  not  present  any  remarkable  dif- 
ference from  the  other;  its  branches  radiate  in  the  same  way 
to  the  diaphragm,  and  supply  its  thickness,  as  well  as  its 
upper  and  under  surfaces.  It  sends  some  filaments  to  the 
lower  part  of  the  oesophagus. 

The  phrenic  gives  ofl'  in  the  neck  a few  filaments  to  the 
scalenus  anticus,  and  the  rectus  anticus  major  muscle.  It 

VoL.  II. — 63 


AEHVOUS  SYSTEM. 


IHcS 

also  communicates  there,  with  filaments  from  the  inferior 
cervical  ganglion,  and  sometimes  from  the  superior  cer- 
vical. 

Of  the  Four  Inferior  Cervical  Nerves. 

The  trunks  of  these  nerves,  on  issuing  from  the  interver- 
tebral foramina,'  have,  one  general  mode  of  distribution, 
which  permits  them  to  be  described  together  or  in  common. 

The  posterior  branches  are  much  smaller  than  those  of  the 
pi’eceding  cervical  nerves;  they  go  backwards  between  the 
complexus  and  the  transversalis  colli,  and  leave  filaments  in 
their  passage  with  them;  they  then  reach  the  splenius  and 
the  trapezius,  to  which  and  to  the  integuments  of  the  neck 
they  are  distributed. 

The  anterior  branches  are  large;  they  appear  on  the  side 
of  the  neck,  between  the  scalenus  anticus,  and  medius  mus- 
cle; sometimes  perforating  the  substance  of  one  or  the  other 
of  these  muscles.  They  each  detach  filaments  to  the  sym- 
pathetic. The  fourth,  also,  commonly  sends  one  to  the 
phrenic.  They  then  form  the  Brachial  Plexus. 

Of  the  Brachial  Plexus  and  the  Nerves  of  the  Upper 
Extremity . 

The  Brachial  or  the  Axillary  Plexus  is  formed  by  the 
junction  and  the  intertexture  of  the  four  inferior  cervical 
nerves,  and  the  first  dorsal  or  thoracic.  It  extends  from  the 
scaleni  muscles,  to  the  axilla  on  a level  with  the  neck  of  the 
os  humeri.  The  nerves  at  first  converge,  and  are  situated 
somewhat  behind  the  subclavian  artery  where  it  passes 
over  the  first  rib;  but  are  at  various  heights  above  it,  ac- 
cording to  their  origin,  with  the  exception  of  the  first  dor- 
sal nerve,  which  has  to  ascend  in  order  to  pass  out  of  the 
thorax. 

The  plexus  is  formed  in  the  following  manner.  The 
fourth  and  the  fifth  cervical  nerves  unite  near  the  scaleni 
muscles  into  a single  trunk,  which  runs  a short  distance 
downwards  and  then  splits  into  two.  The  seventh  cervical 


UPPER  NINE  SPINAL  NERVES. 


499 


and  the  first  dorsal  do  the  same.  The  sixth  cervical  is  the 
central  nerve  of  the  plexus,  and  after  going  downwards  two 
or  three  inches,  it  bifurcates  also.  Combinations  of  these 
primary  divisions  are  formed,  which  are  dissolved  and  then 
re-formed;  in  such  a way  that  a thorough  intertexture  of  the 
original  nerves  takes  place.  This  intertexture  surrounds 
the  axillary  artery  somewhat  like  the  braids  of  a whip-cord, 
from  the  clavicle  to  the  os  humeri  below  its  head.  In  this 
course  the  axillary  plexus  passes  along  with  the  artery  be- 
tween the  subclavius  muscle  and  the  first  rib,  lies  in  con- 
tact with  the  superior  part  of  the  serratus  major  anticus  mus- 
cle, and  immediately  below  the  articulation  of  the  shoulder 
joint.  The  axillary  vein  is  in  front  of  it. 

The  nerves  which  proceed  from  the  axillary  plexus  are 
the  Scapular;  the  Thoracic;  the  Axillary;  the  two  Cutane- 
ous; the  Radial;  the  Ulnar;  and  the  Median.  They  sup- 
ply the  superior  extremity,  including  the  shoulder  and  the 
axilla. 

1.  The  Nervus  Scapiilaris  is  a small  brancli  coming  com- 
monly from  the  upper  part  of  the  plexus,  as  formed  by  the 
fourth  cervical  nerve.  It  goes  backwards  in  company  with 
the  arteria  dorsalis  superior  scapulae,  through  the  notch  or  fo- 
ramen of  the  upper  costa  of  the  scapula;  and  having  thus  got 
to  the  posterior  face  of  the  latter,  it  gives  filaments  to  the  su- 
pra spinatus  muscle;  continuing  its  course  then  on  the  pos- 
terior face  of  the  cervix  scapulas,  it  is  lost  in  filaments  upon 
the  infra-spinatus  and  teres  minor  muscles. 

2.  The  Nervi  Subscapulares  of  Bichat,  present  some 
varieties  in  their  origin;  occasionally  they  come  from  the 
same  trunk,  but  commonly  each  one  has  its  peculiar  root 
from  the  central  parts  of  the  axillary  plexus.  There  are 
generally  three  of  them.  One  of  them  descends  behind  the 
axillary  vessels,  between  the  subscapularis  and  the  serratus 
major  anticus;  it  crosses  the  teres  major,  and  is  lost  upon 
the  contiguous  part  of  the  latissimus  dorsi.  Another  is  dis- 
tributed upon  the  subscapularis  muscle.  The  third  des- 
cends along  the  anterior  margin  of  the  subscapularis  for  a 


500 


NERVOUS  SYSTEM. 


short  distance,  and  distributes  filaments  to  it,  to  the  teres 
minor  and  major  muscles. 

3.  The  Nervi  Thoracici  are  primarily  two  or  three  in 
number,  and  proceed  from  about  the  middle  of  the  plexus. 
The  fasciculi  into  which  they  are  resolved,  may  be  distin- 
guished as  anterior  and  posterior.  The  former  are  distri- 
buted by  filaments,  to  the  subclavian  muscle,  to  the  pecto- 
ralis  minor  and  major,  and  to  the  integuments  covering 
the  latter.  The  posterior  thoracic  has  its  origin  somewhat 
concealed  by  the  scalenus  anticus  muscle.  It  descends  into 
the  axilla,  adhering  to  the  serratus  major  muscle  for  some 
distance,  and  is  then  distributed  by  many  filaments  to  this 
muscle. 

4.  The  Nervus  Axillaris,  or  Circum Jlexus,  comes  from 
the  inferior  part  of  the  plexus.  Immediately  after  its  ori- 
gin, it  goes  downwards  and  outwards  over  the  upper  extre- 
mity of  the  subscapularis  muscle.  It  then  winds  around 
the  os  humeri,  between  the  teres  minor  and  major  muscles, 
observing  the  course  of  the  posterior  circumflex  artery,  and 
finally  terminates  on  the  under  surface  of  the  deltoid  mus- 
cle. 

This  nerve  sometimes  gives  off  the  subscapular,  and  in- 
deed it  is  usual  for  anatomists  to  include  the  description  of 
the  latter  in  it.  As  it  turns  around  the  bone,  it  divides  into 
two  principal  trunjis;  the  superior  goes  to  the  inferior  margin 
of  tfie  infra  spinatus,  and  to  the  posterior  margin  of  the  del- 
toides;  the  inferior  is  distributed  principally  in  the  sub- 
stance of  the  deltoid  muscle,  but  some  of  its  filaments,  b3^ 
perforating  the  latter,  reach  the  skin  and  constitute  the  ner- 
vus cutaneus  humeri.  Filaments  go  from  the  nervus  axil- 
laris, in  the  early  part  of  its  course,  to  the  subscapularis 
and  the  two  teres  muscles. 

5.  The  Nervus  Cutaneus  Internus*  ai’ises  from  the 
lower  part  of  the  axillary  plexus,  and  is  one  of  the  smallest 

* Antonius  and  Caldani,  Tabul.  CCLYIII. 


NERVES  OE  THE  UPPER  EXTREMITY. 


501 


of  those  which  go  to  the  arm.  It  is  situated  between  the 
median  and  the  ulnar  nerve,  and  adheres  almost  as  far  as 
the  elbow,  to  the  basilic  vein.  In  its  descent,  this  nerve  de-^ 
taches  several  small  filaments,  which,  perforating  the  fascia 
of  the  arm,  are  distributed  to  the  integuments  of  the  biceps 
muscle,  and  to  those  on  the  internal  face  of  the  triceps. 

Somewhat  above  the  bend  of  the  elbow,  at  the  place 
where  the  median  basilic  vein  joins  the  basilic,  but  occasion- 
ally some  inches  higher  up,  the  internal  cutaneous  becomes 
superficial  and  splits  into  two  branches  of  nearly  equal  mag- 
nitude, which  diverge  but  little  from  each  other  at  first. 
The  branch  nearest  the  internal  condyle  of  the  os  humeri, 
lies  in  front  of  the  basilic  vein,  as  it  passes  over  the  elbow 
joint;  and  continues  in  this  position  for  two  or  three  inches; 
it  goes  down  the  front  of  the  fore  arm  on  its  ulnar  side,  but 
inclines  continually  to  the  back  of  the  fore  arm.  In  this 
course,  it  detaches  small  ramifications  to  the  integuments 
about  the  internal  condyle,  and  about  the  heads  of  the  flexor 
muscles;  it  also  detaches  continually,  from  its  sides,  small 
filaments  to  the  integuments  of  the  ulnar  side  of  the  fore 
arm  both  anteriorly  and  posteriorly,  some  of  which  reach  to 
the  hand.  The  other,  or  the  external  branch  of  the  inter- 
nal cutaneous,  which  is  nearer  the  radius,  passes  beneath  the 
median  basilic  vein,  about  six  lines  from  the  basilic;  but, 
just  before  it  does  so,  it  detaches  a very  superficial  cutaneous 
filament,  which  crosses  in  front  of  the  median  basilic  vein 
about  its  middle,  and  is  Iqst  a little  below  the  bend  of  the 
arm.  The  radial  branch  of  the  internal  cutaneous  havino- 
got  from  beneath  the  median  basilic  vein,  goes  superficially 
as  far  as  the  middle  of  the  fore  arm  without  sending  off  any 
filaments  of  note;  it  is  then  divided  successively  into  seve- 
ral, which  diverge  to  supply  the  skin  down  to  the  wrist. 

6.  The  Nervus  Musculo-Cutaneus  or  Cufaneus  Exfer- 
nus,  is  somewhat  larger  than  the  preceding,  and  arises  from 
about  the  middle  of  the  brachial  plexus.  It  descends  a 
short  distance,  and  then  perforates  obliquely  the  upper  part 
of  the  coraco-brachialis  muscle.  Having  passed  through 


502 


NERVOUS  SYSTEM. 


this  muscle,  it  continues  its  course  obliquel}'’,  between  tbs 
brachialis  internus  and  the  biceps  flexor,  and  Anally  makes 
its  appearance  superAcially  on  the  outer  side  of  the  tendon 
of  the  latter.  In  this  course,  it  distributes  Alaments  to  the 
several  muscles  with  which  it  is  connected. 

It  afterwards  passes  the  elbow  joint  under  the  median  ce- 
phalic vein  near  its  middle,  and  descends  between  the  skin 
and  the  fascia  of  the  fore  arm,  near  the  outer  margin  of  the 
median  vein,  to  the  hand;  in  this  course  it  is  parallel  with 
and  on  the  front  of  the  supinator  radii  longus.  It  distri- 
butes many  Alaments  to  the  corresponding  integuments  on 
the  radial  side  of  the  fore-arm,  and,  having  at  length  got 
near  the  -lower  end  of  the  radius,  it  divides  into  two  or- 
ders of  Abres,  one  of  which  is  distributed  to  the  integu- 
ments on  the  dorsal,  and  the  other  to  those  on  the  palmar 
side  of  the  hand,  about  the  root  of  the  thumb. 

7.  The  Nerviis  Radialis,  or  Musculo- Spiralis,  arises 
from  the  upper  portion  of  the  brachial  plexus,  but  in  such 
a way  that  Alaments  from  almost  every  part  of  the  latter  run 
into  it.  It  is  a large  trunk  which  winds  spirally  around  the 
os  humeri,  between  the  triceps  muscle  and  the  bone,  enter- 
ing the  Assure  between  the  third . and  the  Arst  head  of  the 
triceps.  It  appears  on  the  outside  of  the  os  humeri,  between 
the  brachialis  internus  and  the  triceps  muscle,  running  for 
some  inches  in  contact  with  their  intermuscular  ligament. 
While  beneath  the  triceps,  it  sends  several  branches  to  its 
heads.  There  are  three  principal  trunks  afterwards  from 
this  nerve. 

a.  The  Ramus  Superflcialis  Dorsalis  is  sent  from  it  on  a 
line  with  the  point  of  the  deltoid  muscle.  This  branch 
then  goes  just  below  the  skin,  parallel  with  and  over  the 
external  ridge  of  the  os  humeri;  it  of  course  crosses  the  ori- 
gin of  the  muscles  of  the  external  condyle.  It  continues 
superAcial  on  the  posterior  external  edge  of  the  supinator 
radii  longus  muscle,  and  terminates  in  the  integuments  on 
the  back  of  the  hand. 

The  continued  trunk  of  the  muscular  spiral  goes  in  the 


JfERVES  01^  THE  UPPER  EXTREMITY. 


, 503 


interstice  between  the  extensor  muscles  of  the  hand  and  the 
brachialis  internus,  and  at  the  external  condyle  divides  into 
the  other  two  branches,  from  which  filaments  proceed  to 
the  contiguous  heads  of  the  muscles. 

b.  The  Ramus  Profundus  Dorsalis  perforates  the  supi- 
nator brevis  muscle,  getting  beneath  the  radial  extensors  to 
the  back  of  the  fore-arm;  it  is  then  distributed  in  numerous 
filaments  to  the  muscles  on  the  back  of  the  fore  arm,  some 
of  its  branches  reaching  to  the  wrist. 

c.  The  Ramus  Superficialis  Anterior  seems  to  be  a con- 
tinuation of  the  main  trunk  of  the  nerve,  and  descending: 
at  the  anterior  margin  of  the  supinator  radii  longus  muscle, 
it  joins  with  the  radial  artery  and  continues  in  its  company 
to  a short  distance  below  the  middle  of  the  radius.  Here 
it  crosses  the  bone  obliquely  beneath  the  tendon  of  the  su- 
pinator longus,  and  then  divides  into  a palmar  and  a dor- 
sal ramuscle;  the  first  being  distributed  to  the  muscles  and 
integuments  of  the  thumb,  the  second  terminating  so  as  to 
supply  the  back  of  the  hand,  of  the  thumb,  fore,  middle, 
and  ring  fingers  to  their  extremities. 

8.  The  Nervus  Medianus,  descends  the  arm  at  the  in- 
ner edge  of  the  biceps  muscle;  along  the  anterior  surface  of 
the  brachial  artery,  adhering  firmly  to  it,  and  the  deep- 
seated  veins,  by  cellular  substance.  As  far  as  the  elbow,  it 
sends  off  no  branch  of  importance.  There  it  lies  at  the  side 
of  the  biceps  tendon,  crosses  the  lower  part  of  the  brachialis 
internus,  and  is  beneath  the  aponeurosis  of  the  biceps.  It 
then  perforates  the  pronator  teres  and  gets  between  the 
flexor  sublimis  digitorum,  and  the  flexor  longus  pollicis,  and 
enters  the  palm  of  the  hand  under  the  ligamentum  carpi,  at 
the  radial  edge  of  the  tendons  of  the  flexor  sublimis.  In 
the  palm  it  is  situated  beneath  the  'aponeurosis  palmaris  and 
the  arcus  sublimis  of  the  arteries. 

The  median  nerve  dispenses  the  following  branches;  At 
the  bend  of  the  arm,  it  furnishes  filaments  to  the  heads  of 
the  first  layer  of  muscles  of  the  fore-arm;  and  a little  below, 
it  detaches  the  nervus  interosseus,  which  supplies  filaments 


50'1 


JNERVOUS  SYSTEM. 


to  the  flexor  longus  pollicis  and  flexor  profundus  digitorum. 
The  interosseous  nerve  then  descends  with  the  interosseous 
artery  in  front  of  the  interosseous  ligament,  and  terminates 
in  the  pronator  quadratus.  Before  the  median  nerve  reaches 
the  wrist  it  sends  a branch  which  supplies  with  filaments, 
the  muscles  and  integuments  of  the  ball  of  the  thumb.  In 
the  palm  of  the  hand  it  divides  and  subdivides  so  as  to  send 
a branch  to  each  side  of  the  thumb,  of  the  fore,  and  of  the 
middle  finger,  and  to  one  side  of  the  ring  finger.  These 
branches  go  along  with  the  arteries  to  the  ends  of  the  fin- 
gers and  thumb. 

9.  The  Nervus  Ulnaris  comes  from  the  lowest  section 
of  the  brachial  plexus.  It  descends  along  the  internal  an- 
terior part  of  the  triceps  muscle,  in  a groove  formed  between 
it  and  the  intermuscular  ligament;  it  diverges  in  this  course 
gradually  from  the  median  nerve  till  it  reaches  the  elbow, 
when  it  is  at  its  greatest  point  of  separation.  At  the  elbow, 
it  is  behind  the  internal  condyle,  in  the  groove  between  it 
and  the  olecranon,  and  separates  the  two  heads  of  the  flexor 
ulnaris  muscle.  It  then  gets  to  the  fore-arm  between  this 
muscle  and  the  flexor  profundus  digitorum,  and  continues 
between  them  to  within  two  inches  of  the  wrist  joint,  when 
it  detaches  the  Ramus  Dorsalis. 

The  Ramus  Dorsalis  slips  between  the  ulna  and  the  ten- 
don of  the  flexor  ulnaris,  I’uns  along  the  internal  margin  of 
the  ulna  to  the  carpus;  it  then  divides  into  ramuscles,  which 
supply  the  ulnar  side  of  the  integuments  on  the  back  of  the 
hand,  and  on  the  backs  of  the  tv/o  last  fingers.  At  the  in- 
terval behind,  between  the  heads  of  the  metacarpal  bones 
of  the  middle  and  ring  fingers,  a considerable  ramuscle  joins 
one  from  the  branch  of  the  muscular  spiral  nerve  which  at- 
tended the  radial  artery. 

The  Ulnar  Nei’ve,  having  given  off  this  dorsal  branch, 
descends  along  the  radial  margin  of  the  tendon  of  the  flexor 
ulnaris  and  the  os  pisiforme,  above  the  annular  ligament, 
to  the  palm  of  the  hand.  Getting  beneath  the  aponeurosis, 
it  there  detaches  first  a deep-seated  branch,  which  penetrates 


THORACIC  SPINAL  NERVES. 


505 

the  muscles  of  the  little  finger  to  supply  them,  the  interos- 
sei,  and  the  short  flexor  of  the  thumb.  The  ulnar  nerve 
then  furnishes  a superficial  branch,  find  afterwards  divides 
into  three;  one  for  the  ulnar  side  of  the  little  finger,  another 
for  the  opposing  sides  of  the  little  and  ring  finger,  and  a third 
which  joins  the  most  internal  digital  branch  of  the  median 
nerve. 


SECT.  II. — OF  THE  THORACIC  SPINAL  NERVES. 

The  Dorsal  or  Thoracic  Spinal  Nerves  {Nervi  Thoracici, 
Dorsales)  consist  in  twelve  pairs,  the  first  pair  goes  through 
the  intervertebral  foramina,  between  the  first  and  the  second 
dorsal  vertebra,  and  the  twelfth  pair  between  the  last  dor- 
sal and  the  first  lumbar  vertebra.  The  common  trunk 
formed  after  the  ganglion  of  each  nerve,  goes  but  a short 
distance  when  it  divides  into  an  anterior  and  a posterior 
branch. 

The  Posterior  Branch  {Ramus  Dorsalis)  of  each  nerve, 
goes  backwards  between  the  transverse  processes  of  the  cor- 
responding vertebrae,  and,  having  got  beneath  the  multifi- 
dus  spinae,  is  commonly  subdivided  into  internal  and  exter- 
nal ramuscles.  The  internal  are  the  smaller,  and  are  dis- 
tributed upon  the  muscles  lying  upon  the  spine,  as  the  mul- 
tifidus,  the  sacro-lumbalis,  longissimus  dorsi,  and  so  on; 
their  terminating  filaments  reach  the  skin.  The  external 
branches  descend  obliquely  outwards  beneath  the  longissi- 
mus dorsi,  and  then  issue  between  the  latter  and  the  sacro- 
lumbalis,  to  both  of  which  they  dispense  filaments;  they 
afterwards  are  divided  into  branches,  which  go  to  the  tra- 
pezius, latissimus  dorsi,  rhomboideus,  and  to  the  corres- 
ponding integuments. 

The  Anterior  Branches  of  the  Dorsal  Nerves  {Rami 
Subcostales)  correspond  with  the  intercostal  spaces  of  the 
ribs.  Each  one,  in  a short  course  after  its  origin,  applies 
itself  to  the,  rib  just  above  it,  and  accompanies  the  intercos- 
tal vessels  in  the  groove,  formed  in  the  under  margin  of 

VoL.  II. — 64 


506 


NERVOUS  SYSTEM. 


eacli  rib.  After  it  proceeds  about  two  thirds  of  the  length 
of  the  rib,  it  separates  gradually  from  it,  and  goes  nearer 
the  middle  of  the  intercostal  space  and  the  superior  margin 
of  the  rib  below.  To  the  angle  of  the  rib,  each  nerve  is 
only  covered  in  front  by  the  pleura,  but  afterwards  it  goes 
between  the  intercostal  muscles.  Near  the  sternum,  the 
branches  become  superficial  by  escaping  from  between  the 
intercostal  muscles,  and  are  distributed  upon  the  pectoral 
muscles  and  the  adjacent  skin.  These  terminating  branches 
of  the  five  or  six  inferior  dorsal  nerves  go  to  the  upper  por- 
tions of  the  abdominal  muscles  and  their  integuments.  Not 
far  from  its  origin,  each  dorsal  nerve  anastomoses  with  the 
ganglion  or  chord  of  the  sympathetic,  after  the  manner  de- 
scribed in  the  account  of  the  latter  nerve. 

There  are  some  differences  between  the  thoracic  nerves 
in  their  manner  of  distribution. 

The  anterior  fasciculus  of  the  first,  as  mentioned,  forms 
the  lower  part  of  the  axillary  plexus  by  joining  itself  to 
the  seventh  cervical.  It  sends  out,  however,  a subcostal 
branch  which  goes  along  the  inferior  face  of  the  first  rib, 
supplying  the  intercostal  muscles  and  having  the  general 
distribution  alluded  to. 

The  Second  Sub-costal  Branch,  besides  the  common  dis- 
tribution, detaches  a fasciculus  which  penetrating  between 
the  ribs,  gets  into  the  axilla  and  is  augmented  by  a branch 
from  the  internal  cutaneous  nerve  of  the  upper  extremity. 
It  then  descends  along  the  internal  posterior  face  of  the  arm 
to  the  elbow,  and  in  this  course  detaches  several  fine  fila- 
ments to  the  integuments. 

The  Third  Subcostal  Branch  in  like  manner  detaches  an 
axillary  fasciculus  which  goes  to  the  inferior  part  of  the 
arm-pit,  to  the  integuments  of  which,  and  to  those  on  the 
internal  face  of  the  arm,  it  is  distributed.  It  does  not  de- 
scend quite  so  low  as  the  preceding.  These  two  nerves  are 
called  Intercosto-Humeral,  and  from  their  origin  and  course, 
are  supposed  to  account  for  the  numbness  of  the  arm,  in 
cases  of  angina  pectoris. 


THORACIC  SPINAL  NERVES. 


507 


The  Fourth,  Fifth,  Sixth,  and  Seventh  Subcostal  Branches 
of  the  Dorsal  or  Thoracic  Nerves,  about  the  middle  of  the 
ribs  to  which  they  respectively  belong,  are  all  divided  into 
two  branches.  One  of  them,  which  is  property  speaking 
the  intercostal,  continues  in  the  inter.costal  space,  giving  fila- 
ments to  its  muscles  and  to  the  triangularis  sterni;  it  then 
emerges  near  the  sternum  to  terminate  upon  the  great  pec- 
toral muscle,  the  mamma  and  the  integuments  of  the  front 
of  the  thorax.  The  other  branch  is  the  external  pectoral, 
it  extricates  itself  earlier  from  the  intercostal  space,  and  is 
distributed  upon  the  muscles  and  the  integuments  on  the 
side  of  the  thorax. 

The  remaining  subcostal  branches,  to  the  eleventh  inclu- 
sively, have  very  much  the  same  principle  of  distribution. 
Their  intercostal  fasciculi,  having  reached  the  anterior  ends 
of  the  intercostal  spaces,  pass  on  to  the  abdominal  parietes, 
between  the  transversalis  muscle  and  the  internal  oblique, 
to  both  of  which  they  give  filaments.  They  reach  the  ex- 
ternal margin  of  the  rectus  abdominis  muscle,  and  then  di- 
vide into  filaments,  some  of  which  go  to  this  muscle,  others 
pierce  the  fore  part  of  its  sheath  and  are  ramified  upon  the 
integuments  of  the  front  of  the  abdomen. 

The  Twelfth  Subcostal  Branch  of  the  Dorsal  Nerves, 
sends  first  a branch  downwards,  which  joins  with  the  first 
lumbar  nerve.  The  subcostal  nei  ve  then  crosses  in  front 
of  the  quadratus  lumborum  muscle,  to  which  it  gives  fila- 
ments as  well  as  to  the  adjoining  portion  of  the  diaphragm. 
It  afterwards  divides  into  two  branches,  the  superior  of 
which  goes  for  some  distance  between  the  two  oblique  mus- 
cles of  the  abdomen,  detaching  filaments  to  them,  and 
finally  terminates  on  the  integuments  of  the  abdomen;  the 
other  branch  goes  between  the  transversalis  and  the  inter- 
nal oblique,  and  is  extended  to  the  lower  part  of  the  rectus, 
and  to  the  pyramidalis  muscle,  to  all  of  which  it  distributes 
filaments. 


506' 


NERVOUS  SYSTEM. 


SECT.  III. — OF  THE  ABDOMINAL  SPINAL  NERVES. 

There  are  five  lumbar,  and  five,  sometimes  six,  sacral 
nerves  on  each  side;  the  first  of  them  passes  out  of  the  in- 
tervertebral foramen,  between  the  first  and  the  second  lum- 
bar vertebra;  and  the  remaining  lumbar  and  sacral  nerves 
go  successively,  through  the  foramina  in  the  loins  and  in 
the  sacrum. 

The  anterior  fasciculi  of  these  nerves,  form  a plexus 
which  extends  from  the  upper  part  of  the  loins  to  the  lower 
part  of  the  sacrum;  it  is  designated  under  the  general  term 
of  Plexus  Cruralis.  The  posterior  fasciculi  are  much  smaller. 
Those  of  the  loins  go  backwards  between  the  transverse 
processes,  and  are  distributed  upon  the  sacro-lumbalis,  the 
longissimus  dorsi,  the  multifidus  spinse,  and  the  correspond- 
ing integuments.  The  posterior  fasciculi  of  the  sacral  nerves 
are  not  so  large,  generally,  as  those  of  the  lumbar;  they  get 
out  through  the  foramina,  on  the  posterior  face  of  the  sa- 
' crum;  are  distributed  to  the  same  muscles;  to  the  origin  of 
the  glutaeus  magnus,  and  to  the  integuments  of  the  sacrum, 
and  of  the  adjoining  portion  of  the  buttocks. 

The  Plexus  Cruralis,  for  tbe  purpose  of  description,  has 
, been  divided  by  anatomists  into  the  Plexus  Lumbalis, 
formed  by  the  four  superior  lumbar  nerves,  and  the  Plexus 
Ischiadicus,  formed  by  the  last  lumbar  and  the  sacral  nerves. 

The  Lumbar  Plexus  {Plexus  Lumbalis)  is  concealed  by 
the  psoas  magnus  muscle,  and  is  placed  between  it,  the  lum- 
bar vertebrae,  and  the  quadratus  lumborum:  frequently  the 
roots  of  the  nerves  forming  this  plexus  penetrate  through 
the  substance  of  the  psoas  magnus  and  form  their  unions 
in  it.  The  plexus  is  narrow  and  pointed  above,  where  it 
commences  by  the  fasciculus  of  the  last  dorsal  nerve  joining 
the  first  lumbar;  but  it  increases  continually  afterwards  in 
breadth,  owing  to  the  nerves  composing  it,  successively 
anastomosing  further  and  further  from  the  spinal  column. 
From  -this  plexus  proceed  three  principal  trunks;  the  upper 
one  {Cruralis  Anterior)  is  of  considerable  size;  and  goes 


ABDOMINAL  SPINAL  NERVES. 


509 


to  the  skin  and  the  muscles  on  the  front  of  the  lower  extre- 
mity; the  middle  {Nervus  Obturator^)  is  not  so  large  as  the 
preceding,  and  goes  through  the  obturator  foramen  to  the 
adductor  muscles  of  the  thigh;  the  inferior,  formed  by  the 
whole  of  the  fifth  and  a fasciculus  from  the  fourth  lumbar 
nerve,  joins  the  upper  part  of  the  sciatic  plexus  in  the  pel- 
vis. Besides  these,  there  are  several  branches  of  smaller 
size  and  of  less  importance,  proceeding  from  the  lumbar 
plexus. 

The  Jlhdomino  Crural  Branches,)  according  to  Bichat, 
are  most  commonly  three  in  number,  and  come  from  the 
two  upper  lumbar  nerves.  The  first  of  them  goes  obliquely 
downwards  and  outwards,  in  front  of  the  quadratus  lumbo- 
rum,  to  the  posterior  part  of  the  spine  of  the  ilium,  and 
runs  for  a short  distance  along  the  crista  of  the  bone:  it 
gives  filaments  to  the  iliacus  internus,  and  to  the  abdominal 
muscles  where  they  border  on  this  part  of  the  bone.  Some 
of  the  filaments  become  cutaneous,  but  the  main  trunk  of 
the  nerve  reaches  the  anterior  superior  spinous  process,  by 
going  between  the  transversalis  and  the  internal  oblique 
muscle;  it  then  follows  the  inguinal  arch  to  the  external 
ring,  through  which  it  passes,  and  is  distributed  in  filaments 
upon  the  groin,  the  pubes,  and  the  scrotum.  The  second 
or  middle  branch  arises  from  the  plexus  near  the  preceding; 
it  descends  along  the  external  margin  of  the  psoas  magnus 
and  crosses  the  iliacus  internus,  covered  by  the  peritoneum; 
near  the  anterior  superior  spinous  process,  it  gets  between 
the  lower  margins  of  the  abdominal  muscles,  and  is  distri- 
buted upon  them  there;  some  of  its  ramifications  get  also 
through  the  external  ring  and  may  be  traced  to  the  scro- 
tum. The  third  or  the  inferior  branch  arises  from  the 
plexus  still  lower  down,  and,  after  having  traversed  the 
front  of  the  iliacus  internus,  it  emerges  from  the  pelvis  be- 
neath Poupart’s  ligament,  near  the  anterior  superior  spinous 
process;  it  then  divides  into  filaments  which  penetrate  to 
the  skin  through  the  femoral  fascia,  and  are  distributed 
along  the  external  anterior  face  of  the  thigh. 


510 


NERVOUS  SYSTEM. 


The  Spermaticus  Externus  arises  from  the  upper  part 
of  the  plexus,  by  a fasciculus  from  the  first  lumbar  nerve, 
which  is  increased  by  one  from  the  second  lumbar.  It  de- 
scends at  first  in  the  body  of  the  psoas  magnus  muscle  and 
then  in  front  of  it;  it  crosses  the  iliacus  internus,  somewhat 
above  Poupart’s  Ligament,  by  directing  its  course  towards 
the  anterior  superior  spinous  process  of  the  ilium.  Here 
it  involves  itself  in  the  edge  of  (he  abdominal  muscles,  and 
goes  on  the  posterior  face  of  Poupart’s  ligament;  at  the  in- 
ternal abdominal  ring  it  joins  the  spermatic  chord  of  the 
male,  or  the  round  ligament  of  the  uterus  of  the  female. 
In  the  first  case  it  is  distributed  to  the  spermatic  chord  and 
scrotum;  in  the  second  to  the  labium  externum  and  mens 
veneris. 

The  Cutaneus  Externihs  arises  from  the  lumbar  plexus 
below  the  external  spermatic'.  It  passes  across  the  iliacus 
internus  towards  the  anterior  superior  spinous  process,  about 
an  inch  below  the  spermaticus  externus,  and  crosses  the 
latter  nerve  just  at  that  process.  Emerging  from  the  ab- 
domen, by  penetrating  the  commencement  of  Poupart’s 
ligament,  it  is  distributed  in  several  branches  to  the  inte- 
guments of  the  vastus  externus  muscle,  and  along  the 
edge  of  the  I'ectus  femoris;  one  of  the  latter  extends  to  the 
patella. 

The  Cutaneus  Medius  is  detached  from  the  anterior  cru- 
ral, an  inch  or  so  above  Poupart’s  ligament.  It  arises  among 
the  cluster  of  branches,  which  come  off  there  to  be  distri- 
buted to  the  iliacus  internus  muscle,  and  to  the  muscles  of 
the  thigh.  It  appears  superficially  on  the  thigh,  for  the 
first  time,  by  penetrating  the  sartorius  muscle,  about  the 
internal  edge  of  the  rectus  femoris;  it  descends  then  along 
the  same  edge  of  the  latter  muscle,  and  is  distributed  to  its 
•integuments.  It  does  not  descend  so  low  as  the  external 
cutaneous. 

The  Cutaneus  interior  arises  also  from  the  crural  nerve. 
It  is  on  the  inner  side  of  the  cutaneus  medius,  emerges 


ABDOMINAL  SPINAL  NERVES. 


511 


from  the  fascia  of  the  thigh,  and  crosses  the  sartorius  mus- 
cle two  or  three  inches  below  the  cutaneus  medius.  It  is 
distributed  on  the  integuments  of  the  vastus  internus  muscle, 
and  some  of  its  branches  extend  to  the  internal  edge  of  the 
patella. 

The  Cutaneus  Internus  arises  from  the  anterior  crural 
nerve,  among  the  same  cluster  above  Poupart’s  ligament. 
It  divides  into  four  or  five  branches  of  different  lengths,  and 
is  distributed  to  the  integuments  of  the  adductor  muscles, 
and  along  the  inner  front  side  of  the  thigh.  One  branch 
observes,  very  much,  the  course  of  the  tendon  of  the  ad- 
ductor magnus,  and  reaches  as  far  down  as  the  inner  side 
of  the  knee. 

The  Cruralis  Anterior  arises  from  the  middle  nerve  of 
the  lumbar  plexus;  at  first  it  is  beneath  the  psoas  magnus 
muscle;  it  then  gets  to  its  outside,  and  passes  from  the  ab- 
domen, under  Poupart’s  ligament,  about  half  an  inch  from 
the  outside  of  the  femoral  artery.  Before  it  reaches  Pou- 
part’s ligament  it  gives  off  a cluster  of  nerves,  several  of 
which  go  to  the  iliacus  internus  muscle;  others  form  the  su- 
perficial or  cutaneous  nerves  of  the  thigh  just  mentioned;  and 
others  the  deep  seated  or  muscular  branches,  which  supply 
the  adductor  muscles,  the  four  extensors,  the  pectineus,  the 
sartorius,  and  the  gracilis. 

One  of  the  branches  of  the  anterior  crural  nerve  is  seen 
to  accompany  the  femoral  artery,  till  the  artery  penetrates 
the  adductor  magnus,  it  then  runs  along  the  front  margin  of 
the  tendon  of  the  adductors  in  a theca  formed  by  this  tendon 
and  the  origin  of  the  vastus  internus.  The  nerve  alluded  to 
is  the  Saphenus;  it  passes  afterwards  between  the  internal 
condyle  of  the  os  femoris  and  the  sartorius  muscle,  attaches 
itself  to  the  saphena  vein,  and  is  distributed  to  the  integu- 
ments of  the  inner  side  of  the  leg,  and  of  the  upper  internal 
parts  of  the  foot. 

The  Nervus  Obturatorius  is  derived  from  the  middle  of 


512 


NERVOUS  SYSTEM. 


the  lumbar  plexus  also;  and  has  very  much  the  same  posi- 
tion, in  regard  to  the  psoas  magnus,.as  the  anterior  crural 
nerve.  It  descends  into  the  pelvis  from  beneath  the  psoas 
magnus,  near  the  sacro-iliac  articulation;  and  passes  for- 
wards and  downwards  to  the  obturator  foramen,  having  got 
through  which,  it  divides  into  an  anterior  and  posterior 
branch.  The  first  is  distributed  to  the  head  of  the  adduc- 
tor longus  and  brevis,  and  to  the  gracilis  and  integuments. 
The  second  terminates  in  the  obturator  externus,  and  the 
adductor  magnus. 

The  Sciatic  Plexus  {Plexus  Ischiadicus,)  is  formed  by 
the  union  of  the  last  lumbar  with  the  four  upper  sacral 
nerves;  the  last  lumbar,  before  it  joins  the  plexus,  receiving 
the  branch  of  the  fourth  lumbar  nerve,  which  is  left  after 
the  lumbar  plexus  is  formed.  This  plexus  is  situated  at  the 
side  of  the  rectum  before  the  pyriformis  muscle. 

The  volume  of  the  posterior  branches  of  the  Sacral  Nerves 
increases  till  the  fourth;  but  the  fifth  and  the  sixth  are  much 
smaller,  in  fact  only  fibrillse. 

The  anterior  branches  of  the  sacral  nerves  are  much 
larger  than  the  posterior.  The  four  first  communicate  with 
the  sacral  ganglions  of  the  great  sympathetic,  besides  form- 
ing the  ischiatic  plexus.  The  third  and  the  fourth,  assisted 
by  the  sympathetic,  form  the  hypogastric  plexus.  The 
fifth,  and  the  sixth  when  it  exists,  are  distributed  to  the 
coccygeus,  sphincter,  and  levator  ani.* 

The  following  small  branches  go  from  the  Sciatic  Plexus.t 

a.  Nervi  Glutsei;  one  passes  through  the  upper  part  of 
the  sciatic  notch  along  with  the  artery,  to  the  glutaeus  me- 

* This  is  only  given  as  the  most  frequent  arrangement  of  the  sciatic  plex- 
us, and  of  the  branches  of  nerves  which  proceed  from  it;  other  arrange- 
ments will  often  be  met  with  in  the  cavity  of  the  pelvis,  in  which  not  so 
many  sacral  nerves  are  sent  to  the  plexus  ischiadicus,  and  the  several 
branches  proceeding  from  it,  depart  in  a different  manner. 

f They  sometimes  come  from  a common  trunk  called,  in  such  case,  the 
Small  Sciatic. 


•i 


ABDOMINAL  SPINAL  NEKVE6, 


513 


dius  and  minimus;  another  below  the  pyriformis  muscle  to 
the  glutasus  magnus. 

h.  Nervus  Pudendalis  Longus  Inferior,  passes  under 
the  tuber  of  the  ischium  to  the  glutseus  magnus;  perineal 
muscles;  urethra  and  integuments  of  the  penis  and  scro- 
tum in  men;  and  to  the  inferior  parts  of  the  labium  exter- 
num in  women. 

c.  Ramus  Femoralis  Cutaneus  Posterior.  This  nerve 
is  placed  between  the  integuments  of  the  thigh,  and  the 
muscles  which  arise  from  the  tuberosity  of  the  ischium.  It 
sends  many  branches  successively  to  the  skin  on  the  back 
of  the  thigh;  one  of  its  branches,  longer  than  the  others, 
goes  down  to  the  ham,  and  there  divides  into  several  fila- 
ments, which  are  distributed  to  the  integuments  on  the  back 
of  the  leg. 

The  Nervus  Pudendalis  Longus  Superior  comes  from 
the  third  and  fourth  sacral.  It  goes  in  company  with  the 
internal  pudic  artery  between  the  sacro-sciatic  ligaments, 
and  then  divides  into  two  branches;  the  inferior  is  distri- 
buted to  the  integuments  and  muscles  of  the  perineum,  to 
the  urethra  and  scrotum;  the  superior  passing  along  the  ra- 
mus of  the  ischium  and  pubes,  with  the  trunk  of  the  inter- 
nal pudic  artery,  is  distributed  to  the  obturator  internus,  ac- 
celerator urinse,  urethra,  and  afterwards  getting  between  the 
symphysis  of  the  pubes  and  the  penis,  terminates  on  its  in- 
teguments and  the  glans  penis. 

The  Nervus  Ischiadicus,  or  the  Great  Sciatic,  is  the  com- 
mon trunk  formed  from  the  sciatic  plexus;  it  is  much  the 
largest  nerve  in  the  body,  and  passes  from  the  pelvis  be- 
tween the  pyriformis  and  the  geminus  superior.  It  crosses 
vertically,  the  small  rotator  muscles  of  the  thigh,  being  con- 
cealed by  the  inferior  edge  of  the  glutaeus  magnus;  it  is  there 
about  balf-way  between  the  tuberosity  of  the  ischium  and 
the  trochanter  major.  Thence  it  descends  on  the  back  of 
the  adductor  magnus,  at  the  outer  edge  of  the  long  head  of 
the  biceps  flexor  cruris.  About  half  way  down  the  thigh, 
sometimes  a little  lower,  the  Sciatic  Nerve  divides  into  the 

VoL.  II. — 65 


514 


NKKVOUS  SVSTEM. 


Popliteal  or  Posterior  Tibial,  and  Peroneal.  Occasionally 
this  division  takes  place  as  high  as  the  exit  of  the  nerve 
from  the  pelvis;  but  in  this  case  the  fasciculi  are  parallel 
with  each  other  as  far  as  the  middle  of  the  thigh.  From 
the  trochanter  minor  to  its  usual  place  of  division,  this  nerve 
is  parallel  with,  and  on  the  back  of  the  thigh  bone;  afterwards 
the  two  branches  begin  to  diverge.  The  popliteal  nerve 
continues  straight  downwards  to  the  back  and  middle  of  the 
knee  joint,  and  to  the  interstice  between  the  heads  of  the 
gastrocnemius  muscle;  whereas  the  peroneal  nerve  goes 
along  the  inner  posterior  edge  of  the  biceps  flexor  cruris, 
and  passes  between  its  tendinous  insertion  and  the  external 
head  of  the  gastrocnemius  muscle. 

In  this  course  the  following  branches  are  sent  from  the 
sciatic. — Twigs  to  the  little  rotator  muscles  of  the  thigh. — > 
The  Cutaneus  Internes  Superior,  which  arises  near  the 
upper  part  of  the  thigh,  and  is  distributed  to  the  skin  of 
of  the  corresponding  part. — The  Cutaneus  Internus  Infe- 
rior, which  arises  just  below  the  last,  and  descending  upon 
the  inner  head  of  the  gastrocnemius,  is  distributed  to  the  in- 
teguments of  the  calf  of  the  leg. — A large  trunk,  and  some- 
times instead  of  it,  distinct  branches  which  go  the  Adduc- 
tor Magnus,  Semi-membranosus,  Biceps,  and  Semitendi- 
nosus. 

The  Peroneal  Nerve  (Nervtis  Peroneus)  divides  at  the 
head  of  the  fibula  into  two  branches,  the  Peroneus  Exter- 
nus  and  the  Tibialis  Anterior;  but,  before  this  division,  it 
sends  a small  branch  to  the  external  parts  of  the  knee  joint 
and  two  cutaneous  branches  called  Peroneo-Cutaneous. 
The  internal  Peroneo-Cutaneo  descends  behind  the  exter- 
nal head  of  the  gastrocnemius,  and,  at  the  bottom  of  the 
leg,  is  united  to  a division  of  the  posterior  tibial  called  the 
External  Saphenus  or  Communicans  Tibiae.  The  exter- 
nal Peroneo-Cutaneous  is  distributed  to  the  skin  along  the 
fibula. 

The  External  Peroneal  Nerve  {Peroneus  Externus')  gets 
between  the  head  of  the  peroneus  longus  and  the  fibula. 


ABDOMINAL  SPINAL  NERVES.  515 

then  between  the  peroneus  longus  and  the  extensor  longus 
digitorum.  It  descends  at  the  outer  edge  of  the  last  mus- 
cle to  the  inferior  third  of  the  leg,  giving  out,  in  the  mean 
time,  many  muscular  branches.  Here  it  penetrates  the  apo- 
neurosis and  divides  into  subcutaneous  branches,  which  sup- 
jily  the  lower  part  of  the  leg,  and  the  upper  surface  of  the 
foot  and  toes.  This  nerve  is  called,  by  the  French,  the 
Musculo-Cutaneous  of  the  leg. 

The  Anterior  Tibial  Nerve  ( Tibialis  ^Anterior)  gets  ob- 
liquely between  the  fibula,  the  peroneus  longus,  and  the  ex- 
tensor longus  digitorum  to  the  front  of  the  interosseous  li- 
gament, where  it  accompanies  the  anterior  tibial  artery.  It 
passes  with  the  artery  under  the  annular  ligament  of  the 
ankle,  has  its  terminating  filaments  going  to  the  muscles  and 
integuments  of  the  upper  surface  of  the  foot,  as  far  as  the 
•end  of  the  two  first  toes.  One  of  its  branches  sinks  down 
with  the  anterior  tibial  artery  to  the  sole  of  the  foot.  High 
up  in  the  leg  it  gives  filaments  to  the  knee  joint,  and,  in  its 
course  downwards,  it  furnishes  the  muscles  on  the  front  of 
the  leg. 

The  Posterior  Tibial  or  Popliteal  Nerve  {Nervus  Popli- 
teiis)  having  the  direction  mentioned,  is  placed  between  the 
skin  and  the  popliteal  vein.  It  gets  between  the  heads  of 
the  gastrocnemius  muscle,  and  perforates  the  origin  of  the 
soleus;  going  with  the  posterior  tibial  artery,  between  this 
muscle  and  the  flexor  longus  digitorum,  to  the  bottom  of 
the  leg.  It  gives  off  the  following  branches: 

a.  The  External  Saphenus  {Saphenus  Externus  or  Com- 
municans  Tibian)  which  arises  above  the  knee  joint,  and, 
descending  between  the  skin  and  the  gastrocnemius,  turns 
outwardly,  and  anastomoses  with  the  cutaneous  branch  al- 
luded to,  of  the  peroneal  nerve.  The  common  trunk  thus 
formed  passes  behind  the  external  ankle,  along  the  external 
margin  of  the  foot,  and  terminates  on  the  last  toes,  having 
given  off  a great  number  of  cutaneous  branches. 

b.  Branches  to  the  heads  of  the  gastrocnemius,  soleus, 
plantaris,  and  popliteus. 


51G 


NERVOUS  SYSTEM. 


c.  Branches  to  the  flexor  longus  digitorum,  tibialis  pos- 
ticus, and  to  the  flexor  longus  pollicis  pedis. 

d.  A branch  through  the  interosseous  ligament,  above,  to 
the  tibialis  anticus. 

e.  At  the  inferior  part  of  the  leg  many  cutaneous  fila- 
ments, one  of  which  gets  to  the  sole  of  the  foot. 

The  Posterior  Tibial  Nerve,  having  given  off  these 
branches,  divides  in  the  hollow  of  the  os  calcis  into  Inter- 
nal and  External  Plantar  Nerves. 

The  Internal  Plantar  {Plantaris  Internus)  proceeds 
alongside  of  the  tendon  of  the  flexor  longus  muscle  of  the 
great  toe  and  the  flexor  longus  digitorum,  and  gives  filaments 
to  the  contiguous  muscles.  It  then  divides  in  such  a way  as 
to  furnish  the  two  sides  of  the  three  first  toes  and  the  inter- 
nal side  of  the  fourth. 

The  External  Plantar  {Plantaris  Externus)  proceeds 
with  the  artery  of  the  same  name  to  the  outer  edge  of  the 
foot,  between  the  flexor  brevis  digitorum  and  the  flexor 
accessorius.  It  is  distributed  to  the  two  sides  of  the  lit- 
tle toe,  and  to  the  external  side  of  the  fourth  toe.  One 
branch  penetrates  to  the  interosseous  muscles  and  to  the 
transversalis  pedis.  A branch  of  considerable  size  is  de- 
tached, near  the  heel,  to  the  muscles  and  integuments  con- 
nected with  the  os  calcis. 


INDEX  TO  VOL.  n. 


Page 


Abdomen  Generally,  ....  - 6 

General  Situation  of  the  Viscera  of,  - 7 

Veins  of,  - - - - ' - 263 

Abdominal  Aorta,  Branches  of,  - - - 218 

Absorbent  Glands  of  the  Abdomen,  ...  303 

Head  and  Neck,  - - 291 

Lower  Extremity,  - - 296 

Upper  Extremity,  - 293 

Thorax,  ...  S09 

Absorbents  of  the  Pelvis,  ....  296 

Head  and  Neck,  ...  £89 


Upper  Extremities  and  the  Contiguous 
Parts  of  the  Trunk  of  the  Body,  - 
Inferior  Extremities  and  the  Contiguous 
Parts  of  the  Trunk  of  the  Body,  - 
Organs  of  Digestion, 

Parietes  of  the  Trunk, 

Viscera  of  the  Thorax, 

.Absorbent  System,  Special  Anatomy  of. 

General  Anatomy  of. 

Accelerator  Urinse,  ..... 

_\orta  and  the  Branches  from  its  Curvature, 

Aqueous  Humour,  . . . = . 

-\queducts  of  Ear,  ..... 

Arachnoidas,  ...... 

Areola,  ...... 

Arcus  Sublimis,  ..... 

Arteries,  ...... 


292 

294 

298 

307 

304 

289 

280 

95 

190 

420 

439 

342 

119 

215 

190 


Texture  of, 

Arteria  Basilaris,  ... 
ad  Cutem  Abdominis,  - 
Alveolaris  Superior, 
Anastomotica,  (Arm,)  - 
-Vnastomotica,  (Thigh,) 
Articularis  Superior  Interna, 

— — Externa, 

— Media, 

— Inferior  Externa, 

— — Interna, 


- 157 
383 

- 236 
202 

- 211 

239 

- 240 

240 

- 240 

241 
. 240 


INDEX. 


Oib 


Page 


Auricularis  Posterior, 

- 

- 

VoL.  IL 

198 

Buccalis, 

- 

- 

- 

202 

Callosa, 

- 

- 

381 

Carotis  Primitiva, 

- 

- 

. 

192 

— Interna, 

- 

- 

- 

193 

— Externa, 

_ 

194 

Cavernosa  Profunda  Penis, 
Caeliaca, 

- 

- 

233 

219 

Centralis  Retinae, 
Cerebri  Posterior, 

- 

- 

- 

383 

Cervicalis  Posterior, 

- 

- 

- 

206 

Choroid  ea. 

- 

- 

381 

Ciliaris, 

- 

- 

- 398- 

-412 

Circumflexa  Anterior,  - 

- 

- 

- 

209 

• — Posterior, 

- 

- 

. 

210 

— Externa, 

- 

- 

• 

237 

— Interna, 

- 

- 

- 

237 

— Ilii,  ^ - 

- 

- 

- 

234 

Colica  Sinistra  Superior, 

- 

- 

- 

223 

— — Media, 

- 

- 

. 

223 

— — Inferior, 

- 

- 

. 

224 

Coinmunicans  Posterior, 

- 

- 

- 

381 

Dentalis  Inferior, 

- 

- 

201 

Dorsalis  Carpi,  - 

- 

- 

- 

213 

— Halucis, 

- 

- 

- 

244 

— Manus, 

- 

- 

- 

215 

Epigastrica, 

- 

- 

234 

Facialis, 

- 

- 

- 

196 

Femoralis,  - 

- 

- 

- 

235 

Frontalis, 

- 

- 

- 

400 

Gastrica, 

- 

- 

- 

219 

Gastrica  Dextra, 

- 

- 

- 

220 

— Sinistra, 

- 

- 

- 

221 

Glutea, 

- 

- 

- 

230 

Haemorrhoidea  Inferior  Externa, 

- 

- 

232 

— Media, 

- 

- 

- 

229 

— Superior  Interna, 

- 

- 

224 

Hepatica, 

- 

- 

- 

220 

Iliaca  Interna, 

- 

- 

- 

227 

— Externa, 

- 

- 

- 

233 

llio-Lumbaris, 

- 

- 

- 

228 

Innominata, 

- 

- 

- 

191 

Intercostalis  Superior, 

- 

- 

- 

204 

Interossea  Anterior, 

- 

- 

- 

214 

— Posterior, 

- 

- 

- 

215 

Infra-Orbitalis, 

_ 

- 

202 

Inferior  Cerebelli,  - 

- 

- 

- 

383 

Ischiadica, 

- 

- 

231 

Lachrymalis, 

- 

- 

- 

398 

Lingualis, 

- 

- 

195 

INDEX. 


519 


Arteria  Magna  Pollicis, 

Mammaria  Interna, 
Maxillaris  Interna, 
Malleolaris  Externa, 

— Interna, 
Mesenterica  Inferior, 
Superior, 

Metatarsea, 

Meningea  Parva, 
Musculares  Orbi tales,  - 
Nutritia, 

Nasalis, 

Obturatoria, 

Occipitalis, 

CEthmoidalis, 

Palatina  Superior, 
Palmaris  Profunda, 
Palpebrales, 

Pedceia, 

Perinea, 

Pharyngea  Inferior, 

— Superior, 
Plantaris  Interna, 

— Externa, 
Poplitea, 

Profunda  Femoris, 
Profunda  Major  Humeri, 
— Minor, 

Pudica  Interna, 

Radialis, 

— Indicis, 
Recurrens  Radialis, 

— Ulnaris, 

Sacra  Media, 

Scapularis,  - 
Superior  Scapulae, 
Spheno-palatina, 
Superficialis  Volae, 
Superior  Cerebelli, 
Splenica, 

Tarsea, 

Temporalis, 

Thyroidea  Inferior, 

— Superior, 
Thoracica  Longa, 

— Acromialis, 

— Axillaris,  - 
— • Superior, 

Tibialis  Anterior, 
Tibialis  Postica, 


Page 
VoL.  II.  213 

- 205 
200 

- 243 

242 

- 223 
221 

- 243 
200 

- 399 
211 

- 400 
228 

- 198 
400 

- 202 
213 

- 400 
244 

- 232 
197 

- 202 
246 

- 246 
239 

- 236 
210 

- 211 

232 

- 212 

213 

- 212 

214 

- 226 
209 

- 207 

203 

- 213 
383 

- 220 

243 

- 199 

204 

- 194 
208 

- 208 
209 

- 208 
242 
. 244 


5£0 


INDEX. 


. - Page 

Ai'teria  Tibialis  Recurrens,  - - Vol.  II.  242 

Tj-inpanica,  - - - - - 200 

Ulnaris,  -----  £13 

Uterina,  - - - . . 230 

Vertebralis,  - - - . 204-382 

Arterias  Bronchiales,  -----  £16 

CEsophageas,  - - - - 217 

Capsulares,  -----  224 

Emulgentes,  - - - - 224 

Gastricse  Breves,  - - . . £21 

Geinellse,  -----  £41 

Intercostales  Inferiores  Aorticse,  - - 217 

Iliacse  Primitivse,  - - - - 227 

Lumbares,  -----  225 

Mediastinales  Posteriores,  - - 217 

Pancreaticse  Mediae  et  Sinistrse,  - - 221 

Phrenicae,  - - - - . 218 

Pterygoidese,  - - _ . - 2OI 

Pudendae  Externae,  . - . 236 

Sacrae  Laterales,  - - - . 228 

Spennaticae,  - - - - 225 

Temporales  Profundae,  - - . 20I 

Vesicales,  - - - . 229 

Arytenoid  Cartilages,  - - - - - 123 

Aryteno-Epiglottideus,  - - - - 127 

Arytenoideus  Obliquus,  . - - . 127 

Transversus,  - - - 127 

Auditory  Nerve,  - - - . . 441 

Axillary  Artery,  Branches  of,  - - - 207 

Biliary  Ducts,  ------  55 

Bile,  ------  56 

Bladder,  ------  74 

Structure  of,  - - . - - 75 

Blood,  -----  . - 168 

Coagulating  Lymph  of,  - - - 173 

Red  Globules  of,  - - - - -173 

Serum  of,  - - - - - 171 

Bones  of  Tympanum,  -----  431 

Brachial  Artery,  Blanches  of,  - - - 210 

Broad  Ligaments  of  the  Uterus,  - - - 110 

Brain,  ------  334 

Veins  of,  - - - - - - 384 

Carotids,  Branches  of,  - - - - 193 

Capillaries,  - - - - - - 153 

Caul,  Situation  of,  . - - - g 

Caecum,  ------  33 

Cerebellum,  - - - - - - 351 

Cerebrum,  ------  324 

Chambers  of  Eye,  - - - - - 422 

Choroidea,  - - - - - . - 405 


INDEX. 


521 


Page 

Chorda  Tympani,  _ _ . 

- 

VoL.  II.  442 

Chylopoietic  Viscera, 

- 

- 

24 

— Assistant, 

- 

. 

48 

Cilia,  _ . . _ 

- 

- 

387 

Circulation  of  the  Foetus,  Peculiarities  of, 

. 

. 

271 

Peculiarities  of, 

connected  with 

its  Nourishment, 

- 

- 

276 

Circulatory  System, 

- 

- 

147 

General  Anatomy  of. 

- 

- 

147 

Considerations  on, 

- 

- 

147 

Special  Anatomy  of. 

- 

148 

Clitoris,  - 

- 

- 

102 

Coccygeus, 

- 

- 

97 

Cochlea,  _ - - - 

- 

- 

436 

Colon,  ----- 

- 

39 

Commissura  Anterior, 

- 

- 

370 

Conjunctiva, 

- 

388 

Corona  Glandis,  . . - 

- 

80 

Cornea, 

_ 

404 

Corpus  Callosum,  . - - 

_ 

361 

Cavernosiim,  - - . 

81 

Ciliare,  - . . 

- 

407 

Dentatum,  - - . 

_ 

353 

Fimbriatum, 

- 

112 

Spongiosum,  - - . 

- 

- 

82 

— Vaginae, 

- 

- 

105 

Corpora  Striata,  - , . 

- 

- 

359 

Crura  Cerebri,  . , . 

- 

357 

Couper’s  Glands,  r . . 

- 

86 

Coronary  Arteries,  - - - 

- 

- 

187 

Veins, 

- 

188 

Cremaster  Muscle,  - - . 

. 

92 

Cricoid  Cartilage,  ... 

« 

122 

Crico-Arytenoideus  Posticus, 

. 

* 

126 

Lateralis,  - 

. 

126 

Crico-Thyroideus,  - - - 

- 

- 

126 

Dartos  Muscle,  - . . 

_ 

* 

88 

Ductus  Ejaculatorius, 

- 

85 

Lactiferi,  - . . 

. 

. 

117 

Duodenum,  - - - . 

33 

Dura  Mater,  - . . _ 

335 

Sinuses  of. 

• 

338 

Ear,  - - - - 

. 

423 

Eminentiae  Mammillares,- 

357 

Olivares,  - - . 

_ 

=. 

347 

Epididymis,  - - - 

- 

91 

Epiglottis,  - . . . 

124 

Erector  Clitoridis,  - - - 

o 

102 

Penis,  ...  - 

- 

- 

95 

voi.  n. 


66 


522 


INDEX. 


Page 

Eustachian  Valve,  - - - - Vol.  II.  179 

Tube,  - - - . . 430 

External  Iliac  Artery,  Branches  of,  - - - 233 

Eye,  385 

Eye-ball,  402 

Eye-lids,  ------  386 

Fallopian  Tubes,  ■ - - - - - 112 

Fcetus,  peculiarities  of,  arising  from  want  of  Respiration,  272 

Fornix,  -------  362 

Fossa  Navicularis,  -----  83 

Ovalis,  ------  179 

Fourchette,  ------  101 

Fourth  Ventricle,  -----  370 

Frsenum  Penis,  -----  80 

Frontal  Nerve,  ------  458 

Fundamental  Portion  of  Cerebellum,  - - 354 

Ganglion  Cavernosum,  - - - - - 481 

Cervicale,  - 482 

Lumbar,  -----  491 

Jjenticular,  - - - - 456 

Spheno-Palatinum,  - - - - 453 

Sacral,  -----  492 

Thoracic,  -----  486 

Gall  Bladder,  - - - - - 55 

Glandulse  Odoriferse  Tysonii,  - - - - 80 

Glandulm  Pacchioni,  . - - - 339 

Palpebrarum,  - - . - 339 

Glandula  Pinealis,  -----  364 

Globus  Major,  - - - - - - 91 

Minor,  -----  91 

Head  and  Neck,  Veins  of,  - - - - 248 

Heart, 177 

Right  Auricle  of,  - - - - - 178 

— Ventricle  of,  - - - - 180 

Left  Auricle  of,  - - - - - 182 

— Ventricle  of,  - - - - 183 

Blood  Vessels  of  - - - - - 187 

Texture  of,  - - - - - 186 

Hymen,  - - - - -•  - IO6 

Ileo-Colic  Valve,  -----  39 

Ileum,  -------34 

Incus,  - - - - - - 431 

Internal  Iliac  Artery,  Branches  of,  - - - 227 

Inguinal  Glands,  - - - - - 296 

Intestinal  Canal,  - - - - - 29 

Intestine,  Small,  -----  29 

Large,  - - - - - 35 

Small,  situation  of,  - - - 8 

Large,  situation  of,  - - ' - 8 

Iris,  ------  410 


INDEX. 


525 


Jpjunem,  .... 
Kidneys,  - - - 

Situation  of,  - - - 

Minute  Structure  of. 

Labia  Interna,  ... 

Externa,  ... 
Labyrinth,  .... 
Lachrymal  Apparatus, 

Caruncle,  ... 
Ducts,  - - - 

Gland, 

Nerve,  - - - 

Sac,  ... 

Larynx,  .... 
Lateral  Ventricles,  - . - 

Levator  Ani, 

Lens,  ..... 
Ligamentum  Ciliare, 

Denticulatum, 

Pal peb rale  Internum, 

Liver,  ..... 
Organization  of, 

Situation  of,  - 
Lower  Extremity,  Veins  of, 

Lungs,  - - . - . 

Texture  of,  - 

Lymphatic  Glands,  . . - 

Malleus,  .... 
Meatus  Externus,  ... 
Mediastinum  Anterior, 

Posterior, 

Superior, 

Medulla  Oblongata,  ... 
Spinalis,  Nerves  of, 

Membrana  Pupillaris,  . . - 

Membrana  Tympani, 

Membranous  Labyrinth, 

Mesentery,  .... 
Mitral  Valve,  - 

Mons  Veneris,  ... 
Mucous  Glands,  and  Apparatus, 

Membranes,  General  Anatomy  of, 
Musculus  Anterior  Auricula,  - 
Antitragicus, 

Attollens  Auriculae,  - 
Corrugator  Supercilii, 

Helicis, 

Laxator  Tympani, 

Levator  Palpebr®, 


Page 
VoL.II.  34 
67 
9 

69 

. 102 
101 
. 434 

392 

- 394 

393 

- 392 
459 

- 395 
121 

- 366 

97 

- 418 
406 

. 332 

386 
48 
51 
8 

261 

- 138 
140 

- 286 
431 

. 423 

144 
. 144 

145 
. 346 

- 323-493 
. 422 

428 

- 437 

35 

- 183 
100 

84 

41 

. 427 

426 

- 427 
000 

- 426 
433 

. 389 


524 


INDEX. 


Musculus  Obliquus  Oculi  Superior, 
— — Inferior,  - 

Orbicularis  Palpebrarum, 
Rectus  Oculi  Superior, 

— — Exiernus, 

— — Inferior, 

— — Internus, 

Retrahens  Auriculas, 
Stapedius, 

Tensor  Tarsi, 

— Timpani, 
Tragicus, 

Transversus  Auriculae, 
Nervous  System,  - . . 

General  Anatomy  of,  - 
Nasal  Nerve,  ... 

Nerves  of  Brain, 

Ear,  ... 

Nervus  Abdomino-cruralis, 
Accessorius, 

Auditorius, 

Cervicalis,  . . 

Circumflexus,  . 

Cruralis  Anterior, 

Cutaneus  Externus, 

— Internus,  - 
— Femoris  Externus, 

— •—  Internus, 

— — Posterior, 

Descendens  Noni, 

Facialis, 

Glosso-Pharyngeus,  - 
Gluteus, 

Hypo  -Glossus, 

Infra  Maxillaris, 

— Orbitalis, 

Ischiadicus, 

Laryngeus  Inferior, 

— Superior, 
Maxillaris  Superior, 
Medianus, 

Motor  Externus, 

— Oculi, 

Nasalis  Internus, 
Naso-Palatinus, 

Obturatorius, 

Olfactorius, 

Opticus,  ... 
Patheticus, 

Peroneus,  ... 


Page 

- 

VoL.  II.  391 

- 

- 

391 

- 

- 387 

- 

- 

■390 

- 

- 390 

- 

. 

390 

- 

- 390 

- 

- 

427 

- 

- 433 

- 

. 

396 

. 

- 433 

- 

- 

426 

- 

- 427 

- 

. 

313 

- 

- 313 

- 

- 

457 

- 

- 371 

- 

. 

440 

- 

- 509 

- 

- 

372-471 

. 

- 374 

- 

- 

494 

■ 500 

. 

. 

511 

- 

- 500 

. 

. 

500 

. 

- 510 

. 

. 

511 

. 

- 513 

. 

- 

470 

- 

374- 

-441-468 

- 

- 

373-473 

- 

- 512 

- 

- 

371-470 

. 

- 464 

- 

. 

460 

- 

- 512 

- 

. 

477 

- 

- 476 

. 

- 

459 

. 

- 503 

- 

- 

375 

. 

- 378 

- 

. 

452 

. 

- 453 

- 

. 

511 

. 

379-450 

- 

. 

378 

. 

- 377 

- 

. 

514 

INDEX. 


0^5 


Nervus  Petrosus  Superficialis,  - 

. 

Page 
VoL.  II.  462 

— Profundus, 
Pharyngeus  Superior,  - 

• 

463 
- 475 

Phrenicus,  - 
Plantaris  Externus, 

497 
- 516 

— Internus, 

- 

516 

Pneu  mogastricus. 

- 

- 

372-474 

Portio  Dura, 

- 

468 

— Mollis,  - 

- 

- 

- 441 

Popliteus,  - - - 

Pudendalis  Superior, 

* 

515 
- 513 

Pterjgo-Palatinus,  - 
Scapularis, 

_ 

461 
- 499 

Spermaticus  Externus, 
Splanchnicus, 

“ 

_ 

510 
- 487 

Subcostalis, 
Suboccipitalis,  - 

505 
- 493 

Subscapularis, 

- 

499 

Sjmpatheticus,  - 

- 

- 480 

Trigeminus, 

Thoracicus, 

- 375-457 
500-505 

Tibialis  Anterior, 
Trochlearis, 

- 

515 

, - 456 

Ulnaris,  ... 

Vidianus, 

- 

504 

462-443 

Neurilemma  of  Nerves, 

Nose,  - - - - 

- 

315 
- 444 

Blood  vessels  of, 
Nerves  of. 

“ 

454 
- 450 

Omenta,  . . - . 

Omentum  Colicum, 

• 

18 

20 

Gastro-S  plenicum, 

Maius,  or  Gastro  Colicum, 

- 

20 

19 

Minus  or  Hepatico  Gastricum, 

- 

18 

Ophthalmic  Nerve, 

- 

- 

- 457 

Optic  Nerve,  - 

Orbit,  Arteries  of. 

. 

“ 

. 

378 
- 398 

Nerves  of,  - 
Veins  of,  - 

398 
- 401 

Os-Orbiculare,  ... 

Organs  of  Assimilation,  - 

- 

. 

432 

5 

Generation, 

— in  the  Male, 

79 

79 

— Female, 

Respiration,  - 

- 

100 

- 121 

Os  Tincae,  - 
Ostium  Venosum, 

“ 

108 
- 183 

Ovaries,  - 

Pancreas,  - - 

" 

113 
- 65 

Situation  of. 

- 

9 

INDEX. 


a£li 


Pancreas,  Minute  Structure  of, 

Papilla,  - 

Pelvic  Fascia,  - - - . 

Penis,  - - - - - 

Pericardium,  - . . . 

Perineal  Fascia,  ... 
Perineum,  Muscles  and  Fascia  of. 
Peritoneum,  - 
Pia  mater,  - 

Pigmentum  Nigrum, 

Pituitary  Gland, 

Membrane, 

Pleura,  - - - - - 

Plexus  Brachialis,  - - . 

Cardiacus,  . . . 

Choroides,  - - . 

Coeliacus,  - - - 

Coronarius,  - - - 

Hepaticus,  . . . 

Ischiadicus,  - - . 

liumbalis, 

Mesentericus  Inferior, 

— Superior,  - 
Phrenicus,  ... 
Renal  is,  . . , 

Solaris,  ... 
Splenicus,  . . . 

Plica  Semilunaris,  ... 
Pori  Biliarii,  . . . . 

Prepuce,  . . 

Primitive  Iliac  Artery,  Branches  of. 
Processus  Ciliaris,  ... 
Prostate  Gland,  - - 

Protuberantia  Annularis, 

Pulmonary  Artery,  . 

Rectum,  .... 
Renal  Capsules,  - . . . 

Minute  structure  of, 
Situation  of. 

Retina,  - - - . 

Round  Ligaments  of  the  Uterus 
Sacculus  Ellipticus, 

Sphericus,  . . . 

Sclerotica,  .... 
Scrotum,  . . . . 

Semicircular  Canals, 

Seminal  Vesicles,  . . . 

Senses,  .... 
Serous  Membranes  generally,  - 

General  Anatomy  of, 


You  II,  66 
119 
99 

79 

- 184 

94 

- 94 
10 

- 343 

408 

- 358 
447 

- 142 
498 

- 485 
345 

- 489 

489 

- 489 
512 

- 508 

490 

- 490 
489 

- 490 
488 

- 489 
394 

52 

80 

- 227 

409 
85 

350 

- 181 

40 

73 

73 

- V 9 

413 

- 110 

438 

- 438 
403 

- 87 
435 

84 

385 

10 


INDEX. 

527- 

Page 

Septum  Lucidum, 

- 

- 

364 

Sinuses  of  Valsalva, 

- 

- 

- 

184 

the  Vertebral  Column, 

- 

- 

- 

256 

Sinus  Cavernosus,  - 

• 

341 

Circularis, 

341 

Lateralis, 

. 

. 

340 

Longitudinalis, 

- 

• 

338 

Occipitalis, 

- 

- 

- 

341 

Petrosus, 

- 

- 

. 

341 

Quartus, 

- 

- 

340 

Soemmering’s  Foramen, 

- 

- 

- 

415 

Spermatic  Chord, 

- 

- 

92 

Sphincter  Ani,  - - 

- 

- 

- 

96 

Vaginae,  - 

- 

- 

105 

Spinal  Marrow, 

- 

- 

- 

323 

Vessels  of. 

- 

- 

- 

333 

Membranes  of, 

- 

- 

. 

329 

Nerves  of, 

- 

- 

- 

327 

Spleen, 

- 

- 

57 

Situation  of. 

- 

- 

8 

Intimate  Structure  of, 

- 

. 

58 

Stapes,  ... 

- 

- 

- 

432 

Stomach,  . . , 

- 

- 

24 

Situation  of. 

- 

• 

8 

Subclavian  Artery,  Branches  of. 

- 

- 

- 

203 

Tarsi,  ... 

- 

- 

- 

387 

Taenia  Striata,  - . - 

- 

- 

361 

Tela  Choroidea, 

345 

Testicles,  ... 

- 

- 

87 

Minute  Structure  of. 

_ 

• 

90 

Thalami  Optici, 

- 

• 

359 

Third  Ventricle, 

_ 

• 

368 

Thymus  Gland, 

- 

- 

. 

138 

Thyreo-Arytenoideus, 

- 

- 

- 

126 

Epiglottideus,  - 

- 

- 

- 

127 

Hyoid  eus. 

- 

- 

- 

126 

Thyroid  Gland, 

* 

- 

. 

135 

Cartilage,  - 

- 

. 

122 

Thoracic  Aorta,  Descending,  Branches  of. 

- 

216 

Ducts, 

- 

- 

• 

310 

Trachea,  ... 

. 

131 

Transversalis  Perinei,  (Male,) 

- 

- 

96 

— (Female,) 

- 

- 

- 

106 

Triangular  Ligament  of  the  Urethra, 

- 

98 

Tubuli  Seminiferi, 

- 

90 

Tuber  Cinereum, 

358 

Tubercula  Quadrigemina, 

. 

- 

• 

365 

Tunica  Albuginea,  - 

. 

• 

90 

Hyaloidea, 

- 

» 

• 

416 

Vaginalis, 

- 

- 

89 

52S 


INDEX. 


Tympanum, 

Umbilical  Artery, 

Vein, 

Upper  Extremity,  Nerves  of, 
Veins  of, 

Ureter, 

Urethra,  (Male,) 

(Female)  . 

Urinary  Organs, 

Uterus  and  its  Appendages, 
Vagina, 

Valve  of  Vieussens, 

Vasa  Arteriarum, 

ElFerentia, 

Recta, 

Vorticosa, 

Vas  Deferens,  . 

Vena  Azygos, 

Axillaris, 

Basilica, 

Cava  Inferior, 

— Superior, 

Cephalica  • 

Choroid  ea. 

Facialis, 

Femoralis, 

Hemiazygos, 

Iliaca  Externa, 

— Interna, 

•—  Primitiva, 
Innominata, 

Intercostales  Superior, 
Jugularis  Externa, 

— Interna, 

Lingual  is. 

Mammalia  Interna, 
Maxillaris  Interna, 
Mediana, 

Meseraica  Inferior, 

— Superior, 
Occipitalis, 

Ophlhalmica,  • 

Palatina  Inferior,  • 
Pharyngea, 

Poplitea,  • 

Portarum, 

Ranina, 

Sacra  Media,  • 

Saphena  Minor  Externa,  • 
— Magna  Interna, 


Page 

428 

277 

276 

498 

258 
72 
82 

103 
67 

107 

104 
352 
162 

91 

91 
409 

92 

255 
260 

259 
266 
253 
259 
409 

248 
262 

256 

263 

264 

265 
253 
255 

251 

252 

249 
255 
251 
259 

269 

270 

250 
401 
249 
249 
261 
269 
249 

266 
262 
262 


IXDEX. 


529 


Vena  Splenica, 

Subclavia, 

Submentales, 

Temporalis, 

— Superficialis, 
Thyroidea  Inferior, 

— Superior, 
Vertebralis, 

Veins,  Texture  of. 

Venae  Capsulares,  • 

Diploicae, 

Emulgentes, 

Hepaticae, 

Lumbales, 

Phrenicae  Inferiores, 
Spermaticae, 

Ventricles  of  the  Brain, 
Verumontanum, 

Visical  Triangle, 

Vestibulum  of  Vulva, 
of  Ear, 

Vitreous  Humour,  . 

Vulva,  . 

Willis,  Circle  of,  . 


I’ag'c 

269 
26  i 

249 

250 
250 
254 

249 
254 
248 
268 

250 
268 
268 
266 
269 

26r 

366 

85 

76 

103 

435 

416 

100 

384 


THB 


VoL.  II. 


67 


1-.. 


I 


W ■ f ''V  - c.-f. 


' w*' 


#■» 


■'k? 


■/f 


■ ;S 


